One police officer was killed and two others wounded Thursday in a shooting on Paris’s famed Champs Elysees, just days ahead of France’s presidential election, police said.

AFP cited France’s interior ministry stating that the gunman was killed after opening fire on the officers on the boulevard. Anti-terror prosecutors have opened an investigation.

“The attacker arrived by car and got out. He opened fire on a police car with an automatic weapon, killing one of the police officers and trying to attack others while running,” a police source told AFP, asking not be named.

The bustling shopping street in the heart of the city was blocked by armed officers and nearby metro stations closed.

The election has long been seen as a potential target of extremists. Witnesses recounted scenes of panic as people ran for cover and sought shelter.

“We had to hide our customers in the basement,” Choukri Chouanine, manager of a restaurant near the site of the shooting, told AFP, saying there was “lots of gunfire.”

Dozens of vehicles from the emergency services were sent to the area, where a helicopter was also deployed.

As the first details filtered through, US President Donald Trump sent his condolences and said that “it looks like another terrorist attack. What can you say? It just never ends.”

The shooting comes two days after the arrest of two men in southern Marseille with weapons and explosives who were suspected of preparing an attack to disrupt the first-round of the presidential election on Sunday.