Paris (CNN) The person who stabbed five people in Paris on Saturday night, killing one, yelled the Arabic phrase "Allahu Akbar," meaning "God is great," during the attack, city prosecutor François Molins told reporters at the scene.

Authorities have opened a terrorism investigation, he said.

Four people were wounded during the knife attack in the touristy 2nd arrondissement, or district, of Paris. It happened around 9 p.m. (3 p.m. ET) , a time when streets and sidewalks were filled with people.

Two of the victims were gravely wounded and two others were lightly injured, police said.

Investigators look through the scene of the attack Saturday night.

The attacker, who French President Emmanuel Macron called a terrorist, is dead, according to police.

Read More