Three people have been charged with assault following a pro-Palestinian rally in downtown Calgary.

The event took place on July 18 on Macleod Trail near city hall. About 400 or 500 Palestinian supporters were on one side of the street near City Hall, while a handful of Israeli supporters were on the other. 

Insp. Cliff O'Brien says it took a while to lay charges because officers had to look at a lot of videos and pictures.

pro-Palestinian rally

Police are looking to identify this man. (Calgary Police Service)

"Investigations are not just about a video or a single photograph. There's a lot of work that has to go into this and we need to be responsible when we're doing this kind of work," he said. 

On Tuesday, three Calgarians were charged with assault: an 18-year-old man, a 27-year-old man and a 16-year-old boy.

Police say they expect a fourth man to be charged.

They also released photos of a man they say may have information about the assaults in hopes someone will be able to identify him.

Several protests recently

There have been a number of protests in Calgary since the conflict started.

Violence broke out at the July 18 pro-Palestinian rally, but Gaza rally organizers later apologized for the violence. 

Then, on July 23, a man was arrested at an Israel solidarity rally for possession of a weapon. The 26-year-old is now facing a number of weapons charges. 

The Calgary for Israel Rally was held on July 31, and featured several speakers like conservative personality and author Ezra Levant. 

The Jewish Defence League of Canada says it has been asked to set up shop in the city, which it hopes to have up and running this month.

Pro-Palestinian supporters also pretended to be victims of the conflict in Gaza at a small protest held near a downtown C-Train platform last Wednesday. 

The protesters were wearing what looked like bloodied clothes and holding signs that say, "Nothing to see here. Just another dead Palestinian."