Police officer with hammer at Notre Dame in Paris

The man attacked Paris police guarding Notre Dame Cathedral Tuesday, crying "This is for Syria" before being shot and wounded by officers outside one of France's most popular tourist sites, authorities said.

At least 600 people were blocked inside the iconic 12th century church while police first secured the streets around it, then combed the pews while visitors sat with their hands raised for the check. Others fled in panic from the sprawling esplanade outside the cathedral.

The assault was the latest act of violence targeting security forces at high-profile sites in France, which remains under a state of emergency after a string of Islamic extremist attacks.

CBS Radio News' Elaine Cobbe reports that the investigation has been handed over to the police's anti-terrorism unit, but the police also said there was no confirmation at this stage whether the incident was a terror attack.

"A person came up behind the police officers, armed with a hammer, and started to hit the police officer," he said.

The man cried, "This is for Syria!" but said nothing else indicating a motive or a link to extremist groups, Collomb said. No group immediately claimed responsibility, and Collomb said he appeared to have acted alone.