Russia launched a large-scale air attack against Ukraine on Monday morning, Ukrainian officials said, pounding several regions with missiles that killed at least two people, wounded at least 33 others and caused heavy damage to residential buildings and industrial sites.

Air raid alerts blared across the country from about 6 a.m. after the Ukrainian Air Force reported the takeoff of nearly 20 Russian fighter jets that then fired cruise, ballistic and hypersonic missiles, in keeping with Moscow’s strategy to overwhelm Ukrainian air defenses with several waves of different types of aerial weapons.

Ihor Klymenko, Ukraine’s interior minister, said that the attack had targeted regions across the country, from Khmelnytskyi in the west to Kharkiv in the northeast, and that private houses had been badly damaged and a shopping center destroyed. He said rescue workers were at the scene of the strikes trying to pull people from under the rubble.

Although the targets of the attack and scale of the damage were not immediately clear, the air assault on Monday came as Russia has stepped up its airstrikes against Ukraine in recent days, in what appears to be a strategy to destroy critical industrial and military infrastructure, and wear down Ukrainian morale.

President Volodymyr Zelensky of Ukraine said last week that Russia had launched some 300 missiles and more than 200 attack drones against Ukraine in a series of attacks around the New Year. The United Nations said on Saturday that 120 civilians had been killed across Ukraine and nearly 480 others injured since Dec. 29.

In Kharkiv, Ukraine’s second-largest city, which is near the border with Russia, missiles “hit the city’s industrial facilities,” starting a fire and injuring at least one woman, said mayor Ihor Terekhov.

The biggest damage appeared to have been caused in the southeastern region of Dnipropetrovsk, where gas stations, administrative and residential buildings, as well as private houses, were hit in strikes that killed a 62-year-old woman and injured at least 24 people, according to Serhii Lysak, the regional governor. Another woman was killed in the Kharkiv region, the authorities there said.

Unlike previous attacks, the Ukrainian capital, Kyiv, was not targeted on Monday. That might be because the city is well protected by powerful air defense systems, including American-designed Patriot batteries, which are able to shoot down most incoming missiles.

But Ukraine’s lack of air defense systems means it has to juggle resources between the front line and cities far from the fighting. As a result, some cities, such as Kryvyi Rih in the Dnipropetrovsk region, which was targeted on Monday, are less well defended.