Three U.S. service members were killed Friday in an attack at the gates of an air base in southern Jordan, U.S. U.S. officials said. 

Reports earlier Friday morning that one or two service members were killed were inaccurate, a U.S. official said.

It was not immediately clear what prompted the shooting.

The shots were fired as a car carrying the Americans as they tried to enter the al-Jafr base near the southern Jordanian town of Mann, according to the Jordanian military. A Jordanian officer was also wounded.

The Americans were in Jordan on a training mission, officials said. The U.S. military typically maintains about 2,000 U.S. forces on the ground in Jordan to support training with the Jordanian military and operations against the Islamic State in neighboring Iraq and Syria.

According to the Congressional Research Service, U.S. assets there include a contingent of U.S. Air Force F-16s and a Patriot missile battery near Jordan's northern border with Syria.

Pro-Western Jordan is a key member of a U.S-led military coalition against the Islamic State group, which controls parts of neighboring Iraq and Syria.

Jordan also faces homegrown extremism, with hundreds of Jordanians fighting alongside ISIS militants in Iraq and Syria and several thousand more supporting the militant group in the kingdom.

Last November, a Jordanian police captain opened fire in an international police training facility, killing two Americans and three others. The government subsequently portrayed the police captain as troubled.

The United States has spent millions of dollars to help the kingdom fortify its borders. For the West, any sign of instability in Jordan, a key ally, would be of great concern.

In late October, a U.S. Army artillery regiment was in Jordan to conduct joint live-fire training with the

M142 High Mobility Artillery Rocket System

, or HIMARS, a mobile, long-range precision strike platform used in Iraq to target Islamic State militants, according to the U.S. Army.

Al-Jafr Air Base is in a remote desert location that is closer to Saudi Arabia than Iraq. It is frequently used for joint U.S. and Jordanian training operations. The U.S. has used the airfield to support air operations in the region.

After the 2001 terrorist attacks on the U.S., the military installation at Al-Jafr was reportedly used by U.S. intelligence officials as a secret prison for the detention, interrogation and torture of suspected terrorists.

The three deaths Friday are the latest in a series of casualties reported from the U.S. Central Command region. Five troops have died in hostile file since Oct. 19.

On Oct. 19 in Afghanistan, Army Sgt. Douglas J. Riney, 26, died in a shooting attack at Camp Morehead, an ammunition supply point outside Kabul.

The shooter was reportedly wearing an Afghan Army uniform. The Riney’s unit was at the base to determine whether the Afghans were tracking their ammunition inventories properly, defense officials said.

On Oct. 20, Navy Chief Petty Officer Jason Finan, 34, was fatally wounded on in northern Iraq in operations near Mosul.

Finan was operating with Kurdish forces when his unit came under attack from small arms fire. Finan was moving to a better position when his vehicle struck an improved explosive device, U.S. officials said.

On Nov. 3 in Afghanistan, two U.S. Special Forces troops were killed in a firefight with the Taliban in Afghanistan’s Kunduz province,

The Associated Press contributed to this report