One officer in serious condition was transported to neighboring Macedonia for neurosurgery, said Maj. Chris Cole, a spokesman for the U.S. peacekeepers in the province. The officer's identity was not disclosed. The other officer in serious condition was being treated at the Kosovska Mitrovica hospital, hospital officials said.
The two were among 11 injured as 21 corrections officers from United States along with two Turks and one Austrian officer came under fire as they were leaving the detention center Saturday after a day of training, said Neeraj Singh, a U.N. spokesman.
At least one member of a group of five Jordanians guarding the prison shot at the officers, and the officers shot back. The attacker and two Americans died in a 10-minute gunbattle. The injured included 10 Americans and the Austrian.
"This is a sad day for United Nations peacekeeping," said Stefan Feller, the head of the U.N. police in Kosovo. He called the shooting a "reckless attack ... that left us in shock and dismay."
Police were investigating the circumstances of the attack, and warned against hasty conclusions concerning a motive.
However, a U.S. police officer serving with the U.N. mission in Kosovo told The Associated Press that the shooting was "clearly an attack against Americans." The officer spoke on condition of anonymity.
The injured U.S. officers were being treated at the main U.S. military base in Kosovo and at the hospital in Kosovska Mitrovica, while the Austrian officer was transferred to a German military base in southern part of the province.
The two dead American officers were women, Singh said. Their names were not released pending notification of their families.
Saturday was the first day at work for the dead and the injured, who belonged to a new U.S. contingent of officers who arrived in Kosovo just 10 days ago.
It was still not clear what sparked the shooting.
"As far as we know, there was no communication between the officer who fired and the group of victims," Singh said.
Four Jordanian police officers had been detained, Feller said. Authorities have requested that the diplomatic immunity of the Jordanian officers be lifted so that they can be interrogated.
Jordan's government expressed regret for the incident and stressed that it is following up on the investigation to uncover details of what had taken place, a statement carried by the official Jordanian Petra agency said. The statement identified the Jordanian U.N. police officer as Ahmed Mustafa Ibrahim Ali, whom police said joined the U.N. police force three weeks ago.
The shootout took place in Kosovska Mitrovica, a city in northern Kosovo that has long been the scene of ethnic violence between Serbs and ethnic Albanians, including riots that broke out a month ago, killing 19 and injuring 900.
The top U.N. official in Kosovo, Harri Holkeri, seemed stunned by the shooting, which occurred as the mission still tries to recover from last month's violence.
"I am deeply shocked and dismayed at the unfortunate death of dedicated professionals who have come such a great distance to help Kosovo on its road to future," he said.
Kosovo became a U.N. protectorate in 1999, after NATO launched a 78-day air war to stop former President Slobodan Milosevic from cracking down on ethnic Albanians seeking independence.
The 3,500-strong U.N. police force includes 450 U.S. officers, most of whom work for Dyncorp, a private company that trains police, corrections and judicial officers who work in places such as Kosovo and Iraq. The U.N. police force works alongside 6,000 local police officers.