At least three people died and 14 were injured following a mass shooting at a bar in Austin, Texas, early on Sunday, police said.

The suspect was killed in an exchange of fire with law enforcers at the scene, police said, adding that 14 people were in hospital, three of whom were in a critical condition.

The man suspected of the shooting had a history of mental health issues, officials said, while the FBI was looking into a possible terrorism link.

Law enforcement officials said the suspect had a history of mental health conditions, according to an internal update from the National Counter-terrorism Centre reviewed by Reuters.

A law enforcement official told Reuters that the shooter wore a shirt with an Iranian flag and IRAN spelled out in green, white and red across the front.

Authorities are investigating whether the suspect was motivated by the joint US-Israel strike on Iran, the official told Reuters.

The shooter was identified as Ndiaga Diagne, a naturalised US citizen from Senegal, according to the Counter-terrorism Centre’s update.

Law enforcement agencies have not identified a specific motive. Alex Doran, acting special agent in charge of the FBI’s San Antonio field office, told reporters on Sunday, “There were indicators on the subject, and in his vehicle, that indicate a potential nexus to terrorism.”

The FBI’s Joint Terrorism Task Force is working with the Austin Police Department on the investigation, which includes staff from the federal agency’s evidence response and digital forensic teams, Doran said at Sunday’s press conference.

United States President Donald Trump has been briefed on the shooting, White House press secretary Karoline Leavitt said in a post on social media on Sunday.

The mass shooting happened outside Buford’s, a popular bar in the West 6th Street stretch of Austin known as the heart of the city’s music and nightlife area, and for its food trucks, according to local media reports.

Austin Police Chief Lisa Davis told reporters the shooter drove an SUV multiple times around the block where the bar is located. At one point, the shooter turned on his hazard lights, rolled down the window and used a pistol to shoot patrons on Buford’s patio and in front of the bar, Davis said. The shooter then drove west, parked the vehicle and got out, and started firing at people who were walking by, she said.

Police officers fatally shot the man at a nearby intersection, Davis said. Law enforcement and emergency services were already in the area because of crowds that tend to gather there on weekends, Davis said. The speed of the response saved multiple lives, she said.

The incident marked the 56th US mass shooting this year and the one with the most victims so far, according to data from the Gun Violence Archive, which defines a mass shooting as an incident in which at least four people, not including the shooter, are injured or killed by gunfire.

The US had 407 mass shootings last year, according to archive data.