三名警察在美国南部城市巴吞鲁日被射杀

A former U.S. Marine has been identified as the gunman who shot and killed three police officers and wounded three others Sunday morning in the southern U.S. city of Baton Rouge, Louisiana.

Military officials say 29-year-old Gavin Long of Kansas City, Missouri was the masked gunman who opened fire on the officers with an assault rifle. He served in the Marines from 2005 to 2010, earning the rank of sergeant. Long was deployed to Iraq from 2008 to 2009. He was killed in the shootout with police.

A fourth officer, a deputy sheriff, remains in critical condition after undergoing emergency surgery. Two other officers received hospital treatment for non-life threatening wounds.

Authorities offered no immediate evidence that police were targeted in the shootings. State Police Superintendent Col. Mike Edmonson said the investigation is ongoing "with a lot of moving parts." He did not rule out the possibility the shooter had one or more accomplices who remain at large.