by Mark Abadi

One police officer was killed and two more were injured in a shooting in Paris on Thursday, multiple news outlets are reporting. According to The Guardian, an attacker 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 tried to run away but was killed by return fire.

A police spokeswoman said the attacker appeared to be acting alone, according to the Associated Press, although Reuters reported that police have issued a warrant for the arrest of a second suspect.  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.  According to police, the shooting was "very probably a terrorist act," ITV reported, and French President Francois Hollande said he was convinced it was "terrorist-related," according to Reuters. But Reuters also cites three police sources who say it may have been an attempted armed robbery, and French Interior Ministry spokesman said it was too early to identify a motive.

The attacker was known to police, a source told The Guardian, and authorities were searching his east Paris home. Police closed off the Champs-Elysee and security vehicles are on the scene, CNN reported. Police are urging the public to avoid the popular shopping area. 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. What can you say — it never ends," he added. This story is developing.