BATON ROUGE, LOUISIANA — Three Baton Rouge police officers were killed and three others injured when a former U.S. Marine went on a shooting spree on Sunday morning.

The gunman was killed in an exchange of gunfire with responding officers. He was named by police as Gavin Long, 29.

Police were called to a convenience store off Airline Highway in Baton Rouge after receiving a report about a man armed with an AR-15 assault rifle, Reuters reported.

Officers appear to have been caught off-guard by Long when he began shooting.

Baton Rouge police named those killed as city officers Montrell Jackson, 32, and Matthew Gerald, 41, and Sheriff’s Deputy Brad Garafola, 45.

Retired Marine sergeant Long reinvented himself as a life coach after he was honorably discharged from the military in 2010, according to the Daily Caller.

Long recently posted a series of online rants under the pseudonym Cosmo Setepenra, urging black people to fight back against perceived police injustices. He posted several videos in recent weeks discussing police shootings, including the death of Alton Sterling in Baton Rouge.

The gunman travelled from his home in Kansas to Dallas earlier this month after Micah Xavier Johnson shot and killed five cops in the Texas city, according to police.

In one video taken down by YouTube after the shootings in Baton Rouge, Long defended the Dallas sniper attack, describing it as “justice.”