Jordanian officer fatally shoots two Americans, South African at security training site

U.S. President Barack Obama said he was treating very seriously the attack at the King Abdullah Training Center, in which three Jordanians and one Lebanese citizen were wounded, and a full investigation was under way.

A senior Jordanian official told Reuters the gunman was a police captain, and authorities identified him as Anwar Abu Zeid. There was no immediate word on the motive for the attack.

Jordan is a staunch U.S. ally in the Washington-led campaign against Islamic State militants who hold large areas of neighboring Syria and Iraq, a position Jordanian officials say leaves the kingdom vulnerable to jihadist attacks.

"This incident sadly does not come as a surprise, as the threat of Islamist terrorism has only increased in the region in the last few years in the aftermath of Syria and Iraq. As much as pre-emptive measures have been taken, it is impossible to eradicate all risks," said a senior Jordanian official who requested anonymity, citing political sensitivities.

The U.S. Embassy in Amman said two American civilian security contractors and a South African contractor were shot to death, and one slain Jordanian was a translator. It was "premature to speculate on motive at this point" with the investigation proceeding, it said.

A second Jordanian, who had been in critical condition, died later of his wounds, Jordan's government said.

There were differing early reports on the number killed, with three U.S. sources saying eight people died in the attack. Jordanian government spokesman Mohammad Momani denied that and Jordan's official death toll stands at six.

A U.S. official said the two Americans were working for the U.S. State Department's International Narcotics and Law Enforcement Affairs Bureau training Palestinian security forces.

The U.S. security contractor DynCorp International confirmed its personnel were fired on during the shooting but did not elaborate.