Stunning video of the incident was shot by a Bay Area man.
A photo shows the suspect on the ground after police shot him. On the ground near him, a backpack can be seen that police say had knives inside and the hammer us allegedly used to attack an officer while shouting "This is for Syria."
RELATED: Attacker with hammer shot near Notre Dame Cathedral, Paris police say
The video shows an officer continuing to point his gun at the suspect after he was down. They say his ID suggests he's a 40-year-old Algerian student.
The video was shot by Los Altos Hills photographer Kyle Riches, who is on vacation with his wife.
ABC7 News spoke with Riches on FaceTime. "I saw two things of smoke. I'm guessing it was just the gunpowder from the two shots we heard. Then probably two or three police officers surrounding a guy who was on the floor at this point and as time went on, I could see blood coming out of his leg," he said.
Meantime, it was frightening for the 600 people inside Notre Dame Cathedral. Police told everyone to show their hands so they could be sure no one had a weapon.
Former President Bill Clinton's United Nations Ambassador Nancy Soderberg happened to be inside. She tweeted that people were calm during the lockdown.
Parisian police say both the attacker and the 23-year-old officer who was hit with the hammer will survive.
They're started a terrorism investigation. The terror threat level remains the same as it's been since a string of attacks in 2015, the highest level possible.