A gunman killed a police officer and injured two more in central Paris on Thursday night

The attacker was killed by return fire

ISIS has claimed responsibility for the attack

Police were searching for a second suspect on Friday morning, a French Interior Ministry spokesman said

The incident happened three days before France's presidential election begins

US President Donald Trump commented on the attack at a press conference

One police officer was killed and two more were injured in a shooting in Paris on Thursday, multiple news outlets reported.

According to The Guardian, an attacker jumped out of a car and opened fire on a police van at around 9 p.m. local time on the Champs-Elysees in central Paris. Reports stated the gunman was using an automatic Kalashnikov rifle. He attempted to flee but was killed by return fire.

French Interior Ministry spokesman Pierre-Henry Brandet said Friday that a second suspect had been identified by Belgian security officials and flagged to French authorities, according to Reuters. The second suspect has handed himself into to Belgian police.

ISIS claimed responsibility for the attack through Amaq, a news agency associated with the terror group. The attacker was known to ISIS as Abu Yussef, or “the Belgian,” according to AFP. The Guardian said the suspect was 39, and his home was in Seine-et-Marne, outside Paris.

The two injured officers are in serious condition, according to Reuters, citing the French Interior Ministry, despite prior reports that one of them had died.

Shortly after the attack, French President Francois Hollande said authorities were convinced it was "terrorist-related," according to Reuters. But Reuters also cited three police sources who say it may have been an attempted armed robbery, and a French Interior Ministry spokesman said it was too early to identify a motive.

"We must all be aware that our security forces do work that is particularly difficult, that they are exposed, as one can see again this evening, and that they have the nation’s full support," Hollande said.

The gunman was a French national who was known to police for "radical Islamist activities," according to CNN. He had shot and wounded three police officers in 2001, and had also been involved in violent robberies, CNN reported. Authorities searched his home in a suburb of eastern Paris on Thursday.

Police closed off the Champs-Elysee and urged the public to avoid the popular shopping area.

People raise their arms to show their hands as they walk towards police on a side road near the Champs Elysees Avenue after a shooting incident in Paris, France, April 20, 2017. REUTERS/Benoit Tessier Security in Paris was increased this week ahead of the French presidential election on Sunday. Two men were arrested on Tuesday for planning an "imminent and violent attack" before the vote. There is no information linking Tuesday's arrests with Thursday's shooting, The Guardian reported.

Two candidates in the French election, Francois Fillon and Marine Le Pen, cancelled campaign events scheduled for Friday, according to ITV.

US President Donald Trump was briefed on the attack and acknowledged it during a press conference on Thursday.

"Condolences from our country to the people of France," Trump said. "It's a terrible thing that's going on in the world today.

"It looks like another terrorist attack. And what can you say — it never ends," he added. "We have to be strong and we have to be vigilant. And I’ve been saying it for a long time."

Peter Jacobs contributed reporting to this story.