(ABC NEWS) -- ISIS claimed responsibility for an attack on police officers on the Champs-Élysées in Paris this evening that left one officer dead and two others wounded.

The terrorist group released a message through its news agency Amaq saying that the attacker was "one of the fighters for the Islamic State."

The assailant was killed but has not been publicly identified, a police spokesperson said.

French President François Hollande said that one bystander was injured during a shootout between police and the attacker and that the leads so far indicated the attack was of a "terrorist nature."

French Interior Ministry spokesman Pierre-Henri Brandet said during a press briefing that a man exited his car and started a shooting at a police car with an automatic weapon around 9 p.m. The attacker continued shooting at police as he attempted to flee the scene and was killed by police in an exchange of gunfire, Brandet said.

A terrorism investigation into the attack had been opened, the Paris prosecutor's office said.

Paris Mayor Anne Hidalgo said that Parisians would not give in to the threat of terrorism.

"Faced with this ordeal, I know that the determination of Parisians to defend their way of life and their values is complete," Hidalgo wrote on Twitter hours after the attack.

Paris police posted tweets earlier in the evening telling people the area around the Avenue des Champs-Élysées was on lockdown and that a police operation was underway.

The U.S. State Department's bureau of consular affairs warned its Twitter followers to avoid the area "after a shooting."

The Champs-Élysées is an iconic boulevard popular with tourists and Parisians alike that has theaters, shops, restaurants and, at one end, the Arc de Triomphe.

President Donald Trump shared "our condolences" with the people of France during a news conference with the Italian prime minister, who was at the White House today.

"It's a very terrible thing that's going on in the world today," Trump said, adding that he thought it was "another terrorist attack," though that had not been confirmed at the time.

"What can you say? It just never ends. We have to be strong, we have to be vigilant," he said.

The incident comes as France heads into a presidential election to be held on Sunday. Several of the major candidates cancelled their scheduled campaign stops for Friday, French daily Le Figaro reported.