The gunman who killed four people—three adults and a child—at an Orange, CA, business locked the gates with a bicycle lock to delay police response.

Officers arriving at the business complex of Unified Homes heard gunfire and could not get through the gates. They secured bolt cutters, went through the gates, and engaged the suspected shooter.

The suspect was wounded in the exchange of fire and arrested. Officials identified the suspect as Aminadab Gaxiola Gonzalez, 44, a resident of the nearby city of Fullerton, Reuters reports.

“The preliminary motive is believed to be related to a business and personal relationship which existed between the suspect and all of the victims. It appears all of the adults were connected either by business or a personal relationship and this was not a random act of violence,” Orange Police Department Lieutenant Jennifer Amat told a news conference.