A sailor who was injured in a shooting in the US state of Tennessee on Thursday has died of his wounds, US media has quoted the navy as saying.

A gunman killed four US Marines and wounded three others, including the sailor, earlier this week after opening fire at two military facilities in the city of Chattanooga.

The navy statement did not give the sailor's name, but he was earlier identified as Navy Petty Officer 2nd Class Randall Smith, a reservist serving on active duty in Chattanooga, the AP news agency said.

The suspect has been identified as 24-year-old Mohammod Youssuf Abdulazeez, a naturalised American born in Kuwait who was shot dead by the police.

Born to Palestinian parents and raised in a Chattanooga suburb, Abdulazeez may have family in Jordan and may have made several stops there, said a government source quoted by the Reuters news agency, adding that a visit to Yemen, long viewed as a training ground for fighters, had not been ruled out.

Investigation continues

Law enforcement officials have said they are investigating whether Abdulazeez was inspired by any armed group. The Islamic State of Iraq and the Levant group had threatened to step up violence during Ramadan.

However, the FBI has stressed it had no indication that the attack was linked to that or any other group.

Investigators believe family or psychological issues may have contributed to the attack, according to a government source, who was not authorised to speak on the record, Reuters said.

Abdulazeez sprayed gunfire at a joint military recruiting centre in an open-air shopping area, then drove to a Naval Reserve Centre about 10km away, where he killed the Marines before he was shot dead. 

The Marine Corps identified the four dead Marines as Gunnery Sergeant Thomas Sullivan of Hampden, Massachusetts, Staff Sergeant David Wyatt of Burke, North Carolina, Sergeant Carson Holmquist of Polk, Wisconsin and reservist Lance Corporal Squire Wells of Cobb, Georgia.

Source: Agencies