SAFETY HARBOR, Fla. (AP) — A pregnant Florida woman fatally stabbed her pit bull when it attacked two other dogs and then turned on her mother and sister.

Pinellas County Sheriff’s officials said in a news release that the attack happened Friday at the family’s home in Safety Harbor, near St. Petersburg on Florida’s Gulf Coast.

Sheriff’s spokesman Spencer Gross says Buster, the pit bull, started attacking two other pit bulls at the home. When 45-year-old Heidi Cooper tried to intervene, Buster attacked her and also turned on Cooper’s 14-year-old Meghan Tokay and Sierra Willson.

Willson then stabbed the dog.

Spencer said the family was treated for bites and other injuries.

Gross said Buster was known to be aggressive and was kept away from the other two pit bulls at the home.