Special operations forces from Iraq, Jordan and the U.S. stand in formation wearing gas masks following a combined demonstration in 2013. (Maya Alleruzzo/AP)

A Jordanian police officer opened fire Monday at a U.S.-backed training center, killing at least five people including two American government contractors, officials said. The gunman also was killed.

The shootings appeared to mark a return of terrorism-linked bloodshed as Jordan commemorated the 10th anniversary of deadly hotel bombings in Amman, the capital.

Jordan’s minister of information, Mohammed Momani, said a South African and two Jordanian employees were among the dead.

At least four others, including two Americans and two Jordanians, were wounded. One of the Americans was listed in “serious condition,” Momani said.

A statement posted by the U.S. Embassy in Amman said it was too early “to speculate on motive at this point.” It added that the embassy has not changed its security posture after the shootings.

Also unclear was any direct connection to the anniversary of the coordinated suicide bombings that killed 60 people and injured more than 100 at three hotels Nov. 9, 2005. Al-Qaeda’s branch in Iraq said it carried out the attacks in retaliation for Jordan’s pro-Western policies.

Jordan’s government-owned al-Rai newspaper described the Americans as contractors but gave no further details. It also identified the attacker as veteran police officer Anwar Bani Abdu, who served as a captain in the Jordanian criminal investigation department before being transferred to the police training academy. The assailant was married with two young children, the newspaper reported.

Jordan is a key Western ally and part of the U.S.-led coalition against the Islamic State. But the latest violence marks another blow to Jordan’s status as a haven of relative stability amid upheavals in neighboring Iraq and Syria.

In Washington, State Department spokesman John Kirby said the two slain American contractors worked for DynCorp International, a private military contracting company headquartered in McLean, Va. Kirby said the two wounded Americans also were State Department contractors but that he did not have details on their employers.

Asked about unconfirmed reports that more people were killed, Kirby said: “The farthest I’m comfortable going right now is to say several people were killed. . . . The numbers have changed a little bit throughout the day. . . . It’s going to be a little fluid. . . . Several killed. Two were American.”

Kirby described the scene of the shootings, the International Police Training Center, as a “Jordanian-owned facility” that was set up mainly to teach Palestinian security forces basic police and security skills. He said it is funded by the State Department and run in partnership with the department’s Diplomatic Security Service and International Narcotics and Law Enforcement Bureau.

President Obama said American officials are taking the attack “very seriously” and will work closely with Jordan for a full investigation. Obama spoke during a meeting with visiting Israeli Prime Minister Benjamin Netanyahu, whose nation has a peace treaty with Jordan.

Jordan runs two highly regarded police training facilities outside the capital. The U.S.-funded Jordan International Police Training Center is instructing police officers who serve in Iraq, Libya and the Palestinian areas of the West Bank. About 75,000 trainees have passed through the facilities.

The Jordan International Police Training Center was established in October 2003 through an agreement between Jordan and the then-provisional government of Iraq, according to a State Department document.

Previous estimates by Jordanian and U.S. officials place the total number of U.S. military and police trainers in Jordan at about 1,000, stationed at air bases, army bases and the police training center.

Over the past two years, Jordan and the United States also have been involved in a problem-plagued training program for Syrian rebel forces that failed to produce an effective fighting force. Washington last month shifted policies to concentrate on assisting militiamen, including Syrian Kurds, who have experience battling the Islamic State.

The attack marks the first deadly strikes against envoys linked to U.S. programs in Jordan since USAID official Lawrence Foley was gunned down in an Amman suburb by al-Qaeda sympathizers in 2002.

On Monday, Jordan’s King Abdullah II visited the wounded at the King Hussein Medical City, the Jordanian royal court said.

Jordan was drawn deeper into the fight against the Islamic State in February after the militants released a video showing a captured Jordanian pilot being burned alive in a cage. The incident sparked widespread anger and revulsion in Jordan and led King Abdullah II to vow “relentless” strikes against Islamic State.

In retaliation for the murder of its pilot, Jordan hanged two convicted terrorists who had ties to the Islamic State. One of those executed was Sajida al-Rishawi, an Iraqi militant, for her role in the 2005 hotel bombings. Rishawi was captured after her suicide belt failed to detonate. Islamic State militants were demanding her release before she was put to death.

Jordan has also cracked down on anyone who waves Islamic State flags or expresses support for the group on the Internet.

Jordanian authorities say the country harbors more than 1.3 million Syrian refugees, 630,000 of whom are registered by the United Nations. Jordan also is home to more than 100,000 Iraqis who have fled conflict in their homeland.

American-linked military and police training sites have faced attacks in the Middle East and elsewhere. The assailants have included officials involved in the training and others posing as members of the facility.

In February, Islamic State militants wearing Iraqi military uniforms tried to storm an air base used by U.S. military advisers to train Iraqi security forces. U.S. officials said most of the attackers were killed.

Booth reported from Jerusalem. Karen DeYoung, Brian Murphy, Carol Morello and Dan Lamothe in Washington contributed to this report.

Read more:

Today's coverage from Post correspondents around the world