-- A hammer-wielding man shouted "This is for Syria" as he attacked an armed police officer patrolling outside near the Notre-Dame Cathedral in Paris today, according to the French interior minister.
A different police officer shot and wounded the attacker, who is now in the hospital, officials said.
French Interior Minister Gerard Collomb said a "three-policeman patrol in charge of surveillance, especially for tourists around Notre-Dame," was on guard when the attacker, armed with a hammer, came up behind one policeman and started hitting him.
Another officer "then reacted with self-control, pulled out immediately and fired," Collomb said.
The suspect was armed with the hammer, kitchen knives and other unsophisticated weapons, said Collomb.
"We've gone from a sophisticated terrorism to a terrorism where any type of tool can be used to attack people," Collomb said.
The assailant was carrying the ID card of an Algerian student, Collomb said, adding that it appeared he acted alone.
The injured officer is recovering in the hospital, police said.
Paris' counter-terrorism office has opened an investigation following the incident, the French prosecutor's office said. Police discovered a video of allegiance to the Islamic State while conducting a subsequent search of a residence linked to the suspect, authorities confirmed Wednesday.
Witnesses to the incident are expected to be questioned, Collomb said.
Visitors who were huddled inside Notre-Dame during the incident were gradually released, police said.
ABC News' Paul Pradier contributed to this report.