File Photo of Barack Obama.
US President Barack Obama said Thursday's "heartbreaking" shootings in Chattanooga that killed four Marines appeared to be the work of a lone gunman.
"We don't know yet all the details, we know that what appears to be a lone gunman carried out these attacks. We have identified a name," Obama said after a briefing from FBI director James Comey.
"It is a heartbreaking circumstance for these individuals who have served our country with great valor to be killed in this fashion," he added, flanked by his top anti-terror advisor, chief of staff and Comey.
Obama said the families were still in the process of being contacted.
"I ask all Americans to pray for the families who are grief-stricken at this point and I want everyone to understand that we will be thorough and prompt in figuring out exactly what happened."
Obama said the FBI would lead the investigation and that the Department of Defense was making sure "all our defense facilities are properly attended and vigilant."