PARIS -- The man who attacked an officer Tuesday at Notre-Dame Cathedral in Paris said, "This is for Syria," French Interior Minister Gerard Collomb said.
The man, believed to be an Algerian student, attacked the officer with a hammer but was also armed with knives, Collomb said.
Collomb said the officer's condition is not serious.
Another officer shot the assailant in the chest, police union spokesman Yves Lefebvre told BFMTV. The attacker was taken to the hospital, and the situation brought under control, police told CNN.
Video posted on social media showed what appears to be the attacker lying motionless on the ground next to a police officer.
The attack caused panic among visitors in the area. France is still in a state of emergency after the November 2015 Paris attacks that killed 130 people. There has been strong police presence on the streets of the capital since then.
Paris is also reeling from an April attack at the Champs-Elysees that left a police officer dead.
Notre-Dame, one of the most popular tourist attractions in Paris, typically attracts long lines of visitors.
Hundreds were holed up inside the cathedral, and photos on social media showed people with their hands in the air.
The Paris prosecutor's office said it had opened an anti-terror probe, and police on Twitter warned the public to stay away from the cathedral.
Kyle Riches, a tourist from San Francisco, was with his wife walking through the plaza outside Notre-Dame when they heard gunshots and dropped to the ground.
"My wife and I ran. We were trying to figure out what was going on," he said.
"We saw SWAT teams coming in to clear the area and started running."
He said he and his wife saw police holding their guns up as they ran toward someone.
A woman in the area at the time said she heard two shots.
"Everyone started fleeing from the cathedral, and police surrounded almost immediately. It looked as though they had surrounded someone at the stairs down to the Seine (River)," said the woman, who gave her name as Abigail M.
"There was a large crowd in line to go into the cathedral, and when the shots fired, they all started running."
She said police had sectioned off an area around the cathedral and down the street.
"We took cover in a nearby store, and they left us there for about 15 minutes before fully clearing the area," she said. "I saw emergency services, military personnel and what appeared to be police dressed in bomb squad gear."