A gunman killed three people in their Philadelphia-area homes and then barricaded himself in a house in New Jersey’s capital city, authorities said, in a string of violence that spread fear among the suburbs and prompted a major police response spanning two states.

The mayhem forced the cancellation of a St. Patrick’s Day parade and shut down a Sesame Street-themed amusement park. Authorities in Pennsylvania’s Bucks County issued a shelter-in-place order for some areas for several hours.

The suspect, identified as 26-year-old Andre Gordon Jr., killed his stepmother, his teenage sister and the mother of his children in shootings that stretched into two homes in eastern Pennsylvania’s Falls Township in the morning, Bucks County District Attorney Jennifer Schorn said.

Officials said they couldn’t yet speak to a motive for the attacks. While Gordon had had some minor brushes with the law, they were “nothing that would indicate that anything like this would happen,” Falls Township Police Chief Nelson Whitney said at a news conference

Police said Gordon was believed to be homeless. It was unclear whether he had an attorney or anyone else who could comment on his behalf.