Authorities have initiated a terrorism investigation to get a better understanding of the Champs Elysees attack in Paris, France.
One police source told Reuters that an arrest warrant has been issued for a supposed second assailant, who is suspected to have arrived by train from Belgium; however, French authorities never confirmed the existence of a second shooter.
According to the interior ministry, a police vehicle was the target of the attack.
French President Francois Hollande reportedly held an emergency meeting with the nation's prime minister and minister of the interior, and will meet with the country's security apparatus on Friday.
One eyewitness described the tragedy as follows for Sky News: The shooter jumped out of an old, grey Audi A80 after parking behind a police van. "He parked just behind the van and he got out with a Kalashnikov and I heard six gunshots. I thought they were firecrackers," the witness added, "because we all looked around the road and there was no one."
The shooter was "hidden behind a van" and shooting at the police, the witness said. "I think he hit a policeman. As soon as the policeman opened the door, he fell, I think."
"As soon as we saw that," the witness said, "we hid and I went up to the first floor." From the new vantage point, the witness reports that the police shot the attacker.
In wake of Thursday's tragic incident, presidential candidates Francois Fillon and Marine Le Pen cancelled previously scheduled campaign events, campaign aides said.
Hollande described the act as "terrorist" in nature and Daesh later claimed responsibility for the shooting.