A gunman has killed three police officers, and wounded three others in Baton Rouge, the capital city of the U.S. state of Louisiana. The officers were attacked after responding to a call of an armed man.

Local police authority said the gunman was killed at the scene after a shootout. The suspect, identified by a U.S. official as former U.S. marine Gavin Long of Kansas City, Missouri, is believed to have acted alone.

This incident comes less than two weeks after a black man was killed by police in the Louisiana capital, sparking nationwide protests—one of which led to the massacre of five Dallas policemen.