It’s a medical nightmare: When the bullets fly not outside on the street, but in the doctor’s office or the hospital itself.

This week’s shooting that left four people dead at a Tulsa medical center is an all-too-familiar scenario for health care workers across the nation, who face assaults and even bullets on the job, according to studies and police reports of at least a dozen shootings across the U.S.

In another hospital attack on Friday, a man stabbed a doctor and two nurses at Encino Hospital Medical Center’s emergency department in the San Fernando Valley of Los Angeles and barricaded himself inside.

“The risk of workplace violence is a serious occupational hazard for nurses and other health care workers,” a recent study by National Nurses United found. “Countless acts of assault, battery, aggression, and threats of violence that routinely take place in health care settings demonstrate a frightening trend of increasing violence faced by health care workers throughout the country.”

On the same day as the Tulsa shooting, a county jail inmate receiving treatment at a Miami Valley, Ohio, hospital stole a security guard’s gun, killed the guard and escaped before fatally shooting himself. And that’s just one of at least six deadly assaults in medical buildings that have happened in Texas, California, New Jersey, Minnesota and elsewhere in the past three years.

‘WE’RE IN A PARALYSIS’:There have already been a dozen mass shootings this year

Researchers have found that the risk of assaults is higher for health care workers than for people in other workplaces, and their risk to become gun violence victims is rising. 

“The frequency with which physicians are injured or killed in acute care hospital shootings has more than tripled during the past two decades,” Maine Medical Center researchers wrote in study they published in April of this year.

Shooting attacks in health settings are usually purposeful and targeted, unlike other types of mass shootings where the attacker doesn’t personally know the victims, research shows. The gunman in Tulsa targeted an orthopedic surgeon who operated on his back, blaming him for persistent back pain, authorities said. 

In some states like Utah, lawmakers currently are considering legislation that would enhance penalties for assaulting healthcare workers, Kaiser Health News reported.