Four Marines were killed when a gunman attacked two military sites in Chattanooga, Tennessee, on Thursday, the U.S. Navy said.

Gunfire was reported at a military recruitment centre in a strip mall as well as the Navy Operational Support Center.

“We are looking at every possible avenue – whether is as terrorism, whether it was domestic or global, or whether it was a simple criminal act”, Reinhold said. He was a hardened mixed-martial-arts fighter who kept a blog where he mused about submitting to Allah.

“We heard one pop, really loud pop. So we went to the door to see what it was”, White told CNN.

According to a federal official, Abdulazeez was a Kuwaiti-born Jordanian who became a naturalized USA citizen.

“I remember him being very creative”.

So did former 10th grade classmate Kagan Wagner, who now lives in Washington state.

At an earlier news conference, Gov. Bill Haslam said it was a “tragic day” for Tennessee.

She never would have thought he could do something like that. “Her parents didn’t approve”, Harper said. “He was pretty popular”.

Wagner believes he was making a joke. The lockdown, she said, “is just a precautionary measure”.

Eventually, the two classmates lost touch after graduation.

Abdulazeez graduated from the University of Tennessee-Chattanooga in 2012.

Devout, but not “overly religious”. He said some of his students had trained with Abdulazeez, although he did not know him well himself.

She said she first heard “Pow, pow, pow!”

He at times interrupted training sessions with fighting coach Schraeder to pray. Other individuals, including a Marine, also were injured and were treated. What made him do what he did will be the subject of intensive inquiries that will delve deep into his past and that of his friends and family, and into his state of mind.

And he may have traveled back to the Middle East in recent years.

Another neighbor, W. Keith Clingan III, said that six or eight months ago, Abdulazeez came roaring up the hill in a Toyota Camry with no hubcaps, driving through a yield sign in front of Clingan’s home. “And I asked his dad about, you know, where’s Mohammad?”

“Sounded like it was 30, 40 shots to me”, Wright said, adding that he never saw a shooter.

Jackson said paramedics were standing by but had not transported anyone at this time. “And we waited until everything seemed to be clear”.

[Breaking news alert, posted at 3:16 p.m. ET Thursday].

“When they actually showed a picture on the news”.

He said Abdulazeez grew up big, more than 6-feet tall, muscular and athletically built.

One officer is “down” in connection with the shooting, Chattanooga Mayor Andy Berke told reporters.

He remembered Abdulazeez and his siblings as well-behaved and polite.

He can’t believe Abdulazeez was radicalized through anyone in Chattanooga. Authorities say there were multiple casualties including the gunman.

Only two posts appear on it, both dated three days prior to the shooting. The attacker was arrested and eventually sentenced to life in prison. That was followed by a second volley of gunfire, he said.

Abdulazeez has been in trouble with the law recently. His court hearing was scheduled for July 30.

The FBI in a statement said the bureau’s Knoxville Field Office, the Chattanooga Police Department and other law enforcement agencies are working jointly to investigate the shootings. He said he was meeting with officials and community leaders to make sure everyone was protected.

FBI special agent Ed Reinhold later clarified that investigators weren’t clear on motive and were treating the shooting as a “terrorism investigation until it can be determined that it was not”.