Seattle police are facing possible legal action after an officer was caught on tape pepper-spraying a man.

It is unclear from the video why the pepper spray was used against the man, who was walking by while on his cell phone.

Police had deployed to a Martin Luther King Day rally that was described as peaceful.

The officer can he heard on the tape, yelling "Get back!" before she sprays the man and a few people next to him.

The man is a high school history teacher and activist named Jesse Hagopian who had just spoken at the rally.

He said he was on the phone with his mother when the incident occurred.

KOMO News reported:

The incident was captured on video and uploaded to YouTube Wednesday, the same day Hagopian's attorney filed a claim against the city. "I felt the piercing pain shoot through my eye, my ear drum and my nostril, all over my cheek and face," Hagopian said, recalling the incident. "I yelled out. My mom was in distress as she heard me yell." Seattle Police spokesman Patrick Michaud said he hadn't seen the video as of Wednesday afternoon and couldn't comment. Michaud said the video was not taken by SPD staff. "(Jesse) was pepper sprayed irrationally by a police officer - no provocation and no reason," said Hagopian's attorney, James Bible. "We view this as a challenge to free speech."

Watch the video below.