Paris: An attacker with an automatic weapon opened fire on police on Paris' iconic Champs-Elysees on Thursday night, killing one officer and seriously wounding three others before police shot and killed him.

ISIS claimed responsibility for the attack. 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.

Paris police spokeswoman Johanna Primevert said that the attacker targeted officers guarding the area near the Franklin Roosevelt subway station at the center of the shopping avenue popular with tourists. She said he appeared to be acting alone.

Police and soldiers sealed off the area, ordering tourists back into their hotels and blocking people from approaching the scene.

The Paris prosecutor's office said counter-terrorism investigators are involved in the probe. Two police officials, speaking on condition of anonymity to discuss the ongoing investigation, said the attacker had been flagged as an extremist. They had no other details about him.

The attack came three days before the first round of balloting in France's tense presidential election. Security is high preceding the vote after police said they arrested two men Tuesday in what they described as a thwarted terror attack.

In Thursday's attack, French Interior Ministry spokesman Pierre-Henry Brandet said on BFM television that a man came out of a car and opened fire on a police vehicle. He said officers were "deliberately" targeted.

Speaking in Washington during a news conference with Italian Prime Minister Paolo Gentiloni, US President Donald Trump said the shooting in Paris "looks like another terrorist attack" and sent condolences to France.

Emergency vehicles blocked the wide avenue lined with shops that cuts across central Paris between the Arc de Triomphe and the Tuileries Gardens, normally packed with cars and tourists. Subway stations were closed off.

The gunfire sent scores of tourists fleeing into side streets. "They were running, running," said 55-year-old Badi Ftati, who lives in the area. "Some were crying. There were tens, maybe even hundreds of them."

Security forces are more widespread in Paris since deadly Islamic extremist attacks in recent years, and France remains under a state of emergency.

French President Francois Hollande scheduled an emergency meeting on Thursday night.

The incident recalled two recent attacks on soldiers providing security at prominent locations around Paris, one at the Louvre museum in February and one at Orly airport last month.

A witness identified only as Ines told French television station BFM that she heard a shooting and saw a man's body on the ground before police quickly evacuated the area where she works in a shop.

A French television station hosting a televised event with the 11 candidates running for president briefly interrupted its broadcast to report the shootings.None of the candidates immediately commented.