A gunman has killed four United States Marines after opening fire at two military facilities in Chattanooga, in the US state of Tennessee, officials said.
The suspect, identified by the FBI as 24-year-old Mohammod Youssuf Abdulazeez, was also killed in the incident on Thursday. Two others, a soldier and a police officer, were wounded, an official said.
US officials said that law enforcement authorities are investigating whether the was inspired by Islamic State of Iraq and the Levant (ISIL) or a similar armed group.
US attorney Bill Killian called the killings an "act of domestic terrorism", though FBI officials said authorities were still investigating a motive.
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The Department of Homeland Security was stepping up security at certain federal facilities "out of an abundance of caution" and supporting the FBI investigation, DHS Secretary Jeh Johnson said in a statement.
Chattanooga is a city of about 173,000 people along the Tennessee River in the southeast of the state.
The US Navy confirmed in a tweet early on Thursday afternoon that a shooting had taken place at a recruitment centre on Amnicola Highway in Chattanooga. Shortly after, the Chattanooga Police Department said the situation had ended.
"Lives have been lost from some faithful people who have been serving our country, and I think I join all Tennesseans in being both sickened and saddened by this," Tennessee Governor Bill Haslam said.
Witnesses and local media reports said the gunman, driving an open-top Ford Mustang, fired at two locations including a military recruiting centre and a US Navy Reserve centre about 10km apart. Witnesses said they heard scores of shots.
US President Barack Obama said early investigations indicated that Abdulazeez was acting alone, but promised a "thorough and prompt" inquiry.
The US Navy confirmed in a tweet early on Thursday afternoon that a shooting had taken place at a recruitment centre on Amnicola Highway [Tim Barber/Chattanooga Times Free Press via AP] 
Source: Al Jazeera and agencies
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