A man with a semiautomatic rifle opened fire at a festival outside a Southern California church Saturday, wounding three people, one of them critically, police said.

Shots rang out shortly before 11 a.m. outside St. John Baptist de la Salle, a Roman Catholic church in Granada Hills, Officer Norma Eisenman said. Bystanders tackled the man and held him until he was taken into police custody, she said.

“He was tackled by an off-duty Burbank police officer” and taken into custody by Los Angeles police, she said.

The gunman wounded three people, including a female who was shot in the elbow, Eisenman said. Two people were taken to a hospital in stable condition and one was in critical condition, she said.

Fire Department spokesman Brian Humphrey said another person was treated for chest pains.

The motive for the attack was not immediately known, Eisenman said.

Church officials did not immediately return calls for comment.