Two St. Paul sisters attacked people in a bus shelter while their mother stood watch armed with a tire iron, according to charges filed Wednesday.

Chellnea K. Fields and Stacie A. Fields, both 19, were each charged by the city attorney's office with third-degree riot and fifth-degree assault in the Oct. 18, 2014, attack.

The girls' mother, Kieviet M. Harris, 39, faces the same charges.

According to the complaint: A Metro Transit police officer was dispatched to the Sunray Transit Center that day about 4:30 p.m. Two people were being assaulted.

Witnesses and security camera footage revealed that the sisters and their mother entered a bus shelter.

"Defendant and her sister immediately started to hit the two victims with their fists," the charges said. "Defendant's mother displayed the tire iron and prevented other people from intervening."

Charges against Harris also allege that she pushed one of the victims with her hips to assist the attack.