Two of the four Marines killed were identified as Skip Wells, 21, and Thomas Sullivan, 40.

However, Cruz urged the public not to dismiss such tragedies as “lone” incidents, connecting the Chattanooga shootings to attacks waged on military facilities in Little Rock, Arkansas, and Fort Hood, Texas, both of which occurred in 2009.

“At the request of the company and in an overabundance of caution, agents conducted a safety check to make sure that nothing remained that would be of harm to employees at that location”, FBI spokesman Joel Siskovic said Thursday night.

The attack is being investigated as “an act of terrorism”.

The FBI said it was dealing with the case as an investigation into domestic terrorism “”until it can be determined that it is not”, but for the moment has not confirmed what motivated Abdulazeez nor has it connected him to any Islamist or jihadist organization”.

Another was Thomas Sullivan, who had survived two tours of duty in Iraq and earned a Purple Heart.

Chattanooga resident David Wyatt was also killed.

Proxmire said her son is being treated at Erlanger Medical Center for three gunshot wounds to the right arm, back and stomach.

The USA military has yet to officially name any of the slain Marines or the wounded sailors.

President Barack Obama called the shootings “heartbreaking” and asked Americans to pray for the relatives of the victims.

Elder said he looked out his window onto the parking lot and saw a man in a silver convertible Mustang, a gun propped out the window, spraying bullets into the storefronts. Abdulazeez was killed during a shoot-out with police.

Dan Walsh, a retired Marine Corps lieutenant and former veterans’ services director for the city of Springfield, said his daughter and Sullivan were classmates at Cathedral.

Investigators were combing through the computer, cellphone and social media contacts of the gunman, identified as Muhammad Youssef Abdulazeez, to determine whether he was in touch with any extremist groups in Jordan before or during this trip.

The Federal Bureau of Investigation remained on the scene Friday collecting evidence.

Floral tributes lay on the ground, as the Tennessee governor blinked into television lights and promised to do all he could to help the families of the victims.

Republican Texas Sen. Ted Cruz labeled the attacks on two military centers in Chattanooga, Tennessee, Thursday that killed four U.S. Marines and injured two others an “act of war”.

But progress is clearly being made. The gunman later died during a firefight with police.

Hours after the first attack, at an all-branches recruiting center, law officers with guns drawn swarmed a house they suspected was Abdulazeez’s in Hixson, Tenn.

Abdulazeez was reportedly born in Kuwait and had Jordanian citizenship, but was also a naturalised U.S. citizen. According to a resume posted online by Abdulazeez, he attended high school in a Chattanooga suburb and graduated from the University of Tennessee in 2012 with an engineering degree.

A woman who went to high school with him said he was a quiet kid and well-liked.

“Tennessee and Chattanooga reacted just as I thought they would, with an outpouring of love”, said Haslam. Majority were never charged with a crime.

A USA official said there was no indication Abdulazeez was on the radar of federal law enforcement before the shootings.