The Islamic State claimed responsibility after one police officer was killed in a rare exchange of gunfire on the famed Champs-Elysees in central Paris just days before a critical presidential election.

Two other officers were seriously wounded in the attack in the popular tourist area in central Paris. The gunman was shot dead by police.

The Islamic State identified the attack as Abu Yusuf al-Beljiki through its Amaq news agency, according to SITE Intel Group, a U.S.-based organization that monitor terrorist activity online.

Paris police spokeswoman Johanna Primevert told The Associated Press that the gunman deliberately targeted police guarding near the Franklin Roosevelt subway station. She said he appeared to be acting alone.

Interior Ministry spokesman Pierre-Henry Brandet told BFM television that a man stepped from a car and opened fire on a police vehicle. A witness told Reuters that the attacker opened fire with a machine gun.

The attack comes three days before the first round of hotly contested presidential elections in France. A French station hosting a televised event with the 11 candidates running for president briefly interrupted its broadcast to report the shootings, AP reported.

Security is high preceding the vote after police arrested two men Tuesday in what they described as a thwarted terror attack.

Two police officers told AP the attacker had been flagged as an extremist, but they offered no further details. The officers spoke to AP on the condition of anonymity to share information about the ongoing investigation.

Authorities were studying potential motives as French prosecutors opened a terrorism investigation into the attack. In Washington, President Trump said the shooting in Paris “looks like another terrorist attack."

As police blocked off key roadways in the heart of the French capital and told people to avoid the area, the broad avenues leading to the Arc de Triomphe were awash in police vehicles decked with whirling blue lights.

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France has lived under a state of emergency declared following a terrorist attack in November 2015 that left 130 dead.