LJUBJLANA, Slovenia — Two American women working as prison guards with the United Nations in Kosovo were killed Saturday, and 10 other Americans and an Austrian working as prison officers were wounded when a Jordanian — also with the United Nations — opened fire on them, officials said.

The attacker was shot and killed.

The attack took place in a prison in the city of Mitrovica, in the north of the province. U.N. officials said the motive for the shooting was not immediately clear.

Some of the wounded were in serious condition, local hospital officials said.

The American dead and wounded were among a group of 21 U.S. prison officers who had arrived April 7 in Kosovo, a U.N. police spokesman said. They had just completed an induction course at the jail, which is usually used as a pretrial detention center for ordinary crimes.

“They were leaving the detention center in three vehicles after a routine training day when they came under fire,” said Neeraj Singh, a spokesman for the U.N. police service in Kosovo.

He said at least one Jordanian officer began shooting and that the Americans returned fire, killing him.

“There was no communication between the two groups before the shooting started,” said Singh, dismissing suggestions in the local media that fighting had erupted as the result of an argument.

Joe Napolitano, commander of a U.N. police station next to the jail, said the Jordanian was able to shoot at the American group for some time before he was killed.

“He just opened fire on them,” Napolitano said. “It lasted about 10 minutes.”

U.N. peacekeepers and police officers have been working in Kosovo since 1999, after NATO’s 78-day bombing campaign to stop forces backed by the former Serbian president, Slobodan Milosevic, from driving ethnic Albanians from the province.

About 3,500 U.N. police officers are in Kosovo.

Jordan has a company of about 120 anti-riot officers in the region. Their duties include guarding the exterior of the prison; they did not serve as guards inside.

The United States has had a lead role in prison administration and staffing in the province.

A statement issued by the U.N. mission in Kosovo confirmed the deaths.

“As a result of the shooting, three international officers died, including two from the United States and one from Jordan,” the statement said. “Eleven other international officers received gunshot wounds and are currently undergoing medical treatment.”

Dr. Milan Ivanovic, director of a hospital in northern Mitrovica where seven of the officers were being treated, said four had suffered serious injuries.

“One American woman is in critical condition,” Ivanovic said.

He said one of the two Americans who died had survived until after arriving at the hospital.

None of the victims was identified.