A gunman wielding an assault rifle on Thursday night killed a police officer on Paris’s most iconic boulevard, the Champs-Élysées, a report said.

The gunman was shot dead by the police as he tried to flee on foot; two other police officers and a bystander were wounded, reported the New York Times.

The police quickly blocked access to the crowded thoroughfare, lined with restaurants and high-end stores, as a helicopter hovered overhead.

The attack set off panic and a scramble for shelter, and officers began searching for possible accomplices after the attack.

Near midnight, President François Hollande said in an address to the nation that the attack appeared to be an act of terrorism. The Islamic State claimed responsibility in a message posted on a jihadi channel, and the Paris prosecutor said he had opened a terrorism investigation.