A Washington state teenager who was riding her bicycle through a mall parking lot when an off-duty officer working as a security guard threw her to the ground and shocked her with a stun gun is suing a police department.

Surveillance video caught the 2014 encounter between Monique Tillman, who's black, and Tacoma Officer Jerad Williams, who's white, and it swept through social media.

The complaint filed last week claims the Police Department's policies lead officers to attack residents. It says supervisors routinely approve "abusive, excessive and unnecessary uses of force."

It expands a lawsuit filed in May and comes when law enforcement agencies nationwide are under fire for treatment of minorities. Tillman's lawyer said they believe the officer's actions were racially motivated.

Department spokeswoman Loretta Cool declined to comment. She says Williams is still employed.