Four US Marines have been killed and one sailor injured during a suspected terrorist shooting at the US Navy's Operational Support Center (NOSC) in Chattanooga, Tennessee.
The shooter, identified as Mohammad Youssuf Abdulazeez, was reportedly carrying 30 round magazines when he opened fire and was armed with an AK-47 style weapon at the time of the attack, according to law enforcement sources.
Abdulazeez was born in Kuwait with a Jordanian citizenship, and was a naturalised US citizen, according to media reports.
According to witnesses, the gunman started shooting at the glass doors of a strip mall military recruitment centre and then headed to an operational support centre operated by the US Navy.
During the shooting episode, the gunman was killed. However, authorities are yet to determine how he died.
US President Barack Obama said in a statement: "It is a heartbreaking circumstance for these individuals who have served our country with great valour to be killed in this fashion.
"My main message right now is, obviously, the deepest sympathies of the American people to the four Marines that have been killed.
"And I want everybody to understand that we will be thorough and prompt in figuring out exactly what happened."
The incident, which has prompted a federal domestic terrorism investigation, follows a similar event in 2014 when four soldiers were killed and 16 others injured at the US Army's Fort Hood base in Killeen, Texas, US.
Secretary of the Navy Ray Mabus said: "The tragedy in Chattanooga is both devastating and senseless.
"While we expect our sailors and Marines to go into harm's way, and they do so without hesitation, an attack at home, in our community, is insidious and unfathomable.
"As the investigation unfolds, our priority will be to take care of the families of those affected."
Image: Police tape and a makeshift memorial at an Armed Forces Career Center, where earlier in the day an active shooter opened fire. Photo: courtesy of US Navy / Damon J. Moritz / Released.