A security guard at a hospital in Kabul opened fire Thursday morning, killing three American doctors—including a father and son—and wounding a U.S. nurse.

"Five doctors had entered the compound of the hospital and were walking toward the building when the guard opened fire on them," Ministry of Health spokesman Kanishka Bektash Torkystani told the Associated Press. "Three foreign doctors were killed."

The third doctor killed in the attack had worked at the Cure International Hospital in Kabul for seven years, according to Afghan Minister of Health Soraya Dalil.

"A child specialist doctor who was working in this hospital for the last seven years for the people of Afghanistan was killed and also two others who were here to meet him," Dalil told the Associated Press.

The gunman—a member of the Afghan Public Protection Force assigned to guard the hospital—reportedly shot himself but survived, according to a Kabul police spokesman.

The U.S. Embassy in Kabul confirmed that three Americans were killed in an attack at the hospital but offered no other information.

The shooting is the second "insider attack" this month in Afghanistan. On April 4, an Afghan police officer shot and killed Anja Niedringhaus, a Pulitzer Prize-winning photographer for The Associated Press. Kathy Gannon, an Associated Press reporter, was wounded in the same attack.

[Image via AP]