It was a grisly scene of bloody limbs and crumpled vehicles as a series of Russian mines exploded across a field in southern Ukraine.

One Ukrainian soldier stepped on a mine and tumbled onto the grass in the buffer zone between the two armies. Nearby lay other Ukrainian troops, their legs in tourniquets, waiting for medical evacuation, according to videos posted online and the accounts of several soldiers involved.

Soon, an armored vehicle arrived to rescue them. A medic jumped out to treat the wounded and knelt on ground he deemed safe — only to trigger another mine with his knee.

Five weeks into a counteroffensive that even Ukrainian officials say is off to a halting start, interviews with commanders and soldiers fighting along the front indicate the slow progress comes down to one major problem: land mines.

The fields Ukrainian forces must cross are littered with dozens of types of mines — made of plastic and metal, shaped like tins of chewing tobacco or soda cans, and with colorful names like “the witch” and “the leaf.”

Ukraine’s army is also hindered by a lack of air support and the deep network of defensive structures the Russians have built. But it is the vast array of mines, trip wires, booby traps and improvised explosive devices that has Ukrainian forces bogged down only a few miles from where they started.

“I couldn’t imagine something like this,” said a Ukrainian private named Serhiy, part of a unit that rescued the soldiers wounded by the explosions. “I thought mines would be lain in lines. But whole fields are filled with them, everywhere.”

Mines have long been a staple of Russian warfare, used extensively in Afghanistan and Chechnya and earlier phases of the fighting in Ukraine, stretching back to 2014. But the minefields in southern Ukraine are vast and complex, beyond what had been previously known, soldiers who have entered them say. Ukraine also plants expansive fields of antitank mines, to stop Russian advances.

“To clear mines, you should have a lot of motivation and a cool head,” said Maj. Maksym Prysyazhnyuk, a Ukrainian demining expert who slips into the fields at night ahead of infantry advances. “It’s such delicate work, like of a surgeon, but at the same time, explosions are going off all around you” from artillery in the battle.

Demining specialists venture out with metal detectors and long, slender probes attached to poles, to gingerly poke at the ground to try to find buried mines without setting them off. “These are our tools — and an icon in the pocket,” said Major Prysyazhnyuk, referring to Orthodox religious images. He was at a medical stabilization point where soldiers wounded by mines turned up in a steady stream.

The minefields are routinely set with booby traps and so-called anti-handling devices that cause mines to detonate if they are lifted, to thwart demining teams. A common tactic is what Major Prysyazhnyuk called a “trick for idiots” — burying anti-personnel mines in front of a trip wire, to target a soldier who might try to disable the trip wire.

More sophisticated explosives include the so-called jumping mines, which, when stepped on, pop up and spray shrapnel, hitting other soldiers nearby. Russia also uses mines triggered by slender, yellow-colored trip wires that stretch out a dozen or so yards, any of which when disturbed can set off an explosion and a spray of shrapnel.

The demining teams work by clearing a path about two feet wide, allowing the infantry to walk forward. Then, the de-miners work back along the path to expand it by another foot or more, to allow two soldiers to walk shoulder-to-shoulder while carrying a stretcher for soldiers wounded in the fight. Last month, a stretcher bearer carrying a wounded colleague triggered a mine because the path could not be widened quickly enough.

Danger exists even after the paths are cleared. Russian forces often fire rockets that scatter small, hard-to-spot green plastic “leaf” mines, also called butterfly mines, over the cleared area, Major Prysyazhnyuk said.

Volodymyr, who serves as a military medic at the stabilization point, performs amputations on soldiers whose feet or lower legs have been shorn off by mine explosions.

Mines, he said, have surpassed artillery as a leading cause of wounds. Because some mines are plastic, to avoid detection by demining teams, the shrapnel they spray into soldiers can be invisible to doctors in first-aid stations near the front, where medical teams use metal detectors to find and remove fragments, he said.

Like other soldiers interviewed, he spoke on the condition that he be identified by only his first name, for security reasons.

The soldiers are treated and sent to hospitals farther away. Last week, Volodymyr said, he amputated both hands of a demining expert who was wounded while trying to defuse a booby-trapped mine.

The past month has been a harrowing, difficult phase of the war for the Ukrainian army, which is under pressure to advance quickly and demonstrate to Western allies that the policy of arming Ukraine can turn the tide.

In his nightly address on Friday, President Volodymyr Zelensky again defended the pace of the counteroffensive, saying that Russia was throwing “everything they can” at Kyiv’s troops, and that “every thousand meters of advance” deserves gratitude.

In the south, Ukrainian troops are attacking in at least three locations but have not broken through the Russians’ main lines of defense. Mines are not the only difficulty they face. As they advance, Ukrainian soldiers move out of range of some of their air-defense systems and become vulnerable to Russian attack helicopters.

By this week, at its farthest point of advance, south of the village of Velyka Novosilka, the Ukrainian army had pushed a bulge about five miles deep into Russian lines. At the point where the soldiers became stranded in a minefield, south of the town of Orikhiv, Ukraine has advanced about a mile. To reach the Sea of Azov and cut supply lines to Russian-occupied Crimea, an objective in the counteroffensive, Ukraine must advance about 60 miles.

One bright spot as they fight through the minefields, Ukrainian soldiers say, is the protection provided by Western armored vehicles.

Where they have been used, these vehicles have not enabled the Ukrainian military to cross minefields, but they have saved lives with superior armor that protects against the blasts.

The American-made Bradley infantry fighting vehicles, with layered aluminum and steel armor, roll over anti-personnel mines with impunity. They are immobilized by Russian antitank mines, hefty circular devices that are laden with about 15 pounds of TNT, often without causing serious injury to the soldiers inside.

Denys, a military surgeon at another stabilization point near the front, said troops injured by mine explosions while riding in Bradleys fared much better than those in Soviet-legacy armored vehicles, and that the main consequence was a concussion rather than the loss of a limb.

“The Americans made this machine to save the lives of the crew,” said Serhiy, the private on the rescue team, who is now operating in his third Bradley after two earlier vehicles hit antitank mines. The second occurred when he and others were sent to evacuate wounded infantry stranded in a minefield.

The series of explosions was filmed by a Ukrainian drone and the footage posted online by a Ukrainian journalist. The episode was also described to The New York Times by Serhiy and other witnesses.

Driving into the minefield, the Bradley crew could hear over the rumble of the engine the pop of the less powerful anti-personnel mines exploding harmlessly as the vehicle’s tracks ran them over. To avoid antitank mines, they tried to follow tracks left by other vehicles that had driven into the field, but it was difficult.

Once they reached the wounded soldiers, a gunner, Serhiy, and a sergeant, also named Serhiy, focused first on shooting back at Russian machine gun positions in a distant tree line that were firing on the soldiers pinned down in the minefield.

The medic, meanwhile, jumped into an artillery crater, apparently assuming the crater was clear of anti-personnel mines. He knelt and set one off, blowing off part of his leg.

The drone footage shows the medic applying a tourniquet to his maimed leg, then crawling back toward the Bradley, where another medic helps pull him aboard, leaving a streak of blood on the ramp.

Inside the Bradley, other medics put on a second tourniquet, Sergeant Serhiy said. Throughout the ordeal, which stretched to three hours, he had to leave the vehicle at times to carry casualties.

“It was scary to step out when you just saw somebody blown up on a mine,” he said.

As they drove out of the field, the Bradley hit an antitank mine and skidded to a stop. The explosion damaged the rear ramp, so the crew opened a hatch on the roof and lifted the wounded men through it, then lowered them to the ground. They then helped them limp toward another Bradley that drove them to safety.

Sergeant Serhiy returned to the site a few days later with an armored tow truck to retrieve the Bradley. As it was being pulled out, the Bradley rolled over another antitank mine, causing more damage.

The vehicle is now in Poland for repairs, Sergeant Serhiy said. He received another Bradley to continue the attempted advances over the minefields.

Maria Varenikova contributed reporting from Orikhiv, Ukraine.