A driver behind the wheel of a pickup truck rammed into a crowd of New Orleans revelers on Bourbon Street early on New Year’s Day, killing 10 people in what the FBI is investigating as an act of terrorism.

After the vehicle stopped, the driver emerged from the truck and opened fire on responding officers, New Orleans police said.

The FBI confirmed that it has identified the driver as 42-year-old Shamsud-Din Bahar Jabbar. Investigators are working to gather additional information about Jabbar’s background and investigating an Islamic State flag that was with the vehicle, the FBI said.

The ISIS flag was recovered in the vehicle used by Jabbar, the FBI said in a statement.

The FBI says it is still investigating the attacker, a U.S. citizen from Texas, to determine “potential associations and affiliations with terrorist organizations.”

A photo circulated among law enforcement officials showed a bearded Jabbar wearing camouflage next to the truck after he was killed by police.

Jabbar was killed in a firefight with police following the attack around 3:15 a.m. in an area teeming with New Year’s revelers, the FBI said.

This is a developing story and will be updated.