A suspect has barricaded himself in a home in New Jersey and is holding hostages after allegedly shooting three people dead in suburban Philadelphia.

The Saturday morning shooting in Falls Township in eastern Pennsylvania forced the cancellation of a St Patrick’s Day parade and shut down a children’s theme park.

Authorities in Bucks County issued a shelter-in-place order for the area for several hours, but it was cancelled by early afternoon.

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 could not 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.

After fleeing in a stolen car, then taking another in a carjacking in a car park, Gordon holed up in a home in nearby Trenton, New Jersey, authorities said.

By mid-afternoon, officers surrounded the house on a taped-off block, calling to Gordon through a loudspeaker and trying to persuade him to come out.

The home’s residents had been taken to safety with no injuries, the Trenton Police Department said.

Ms Schorn said Gordon first broke into a home in the Falls Township community of Levittown and killed his 52-year-old stepmother, Karen Gordon, and his 13-year-old sister, Kera Gordon.

Three other occupants, including a 14-year-old, hid as the suspect went through the house, searching for them, the district attorney said.

She said Gordon then drove to another home in Levittown and shot and killed 25-year-old Taylor Daniel, the mother of his two children, who were present. The victim’s mother was bludgeoned with a rifle, Ms Schorn said. Police said the injured woman is expected to recover.

Ms Schorn said that after the shootings, Gordon carjacked a vehicle in Morristown, Pennsylvania, from a 44-year-old man who was not harmed. From there, officials said, Gordon drove to the home in Trenton.

Middletown Township police said the suspect has ties to addresses in Bucks and Trenton and “stays in Trenton primarily”.

Pennsylvania governor Josh Shapiro said in social media posts that he has asked the Pennsylvania State Police to assist local law enforcement agencies.

Police said Oxford Valley Mall and Sesame Place had been told to close until further notice, and the area’s Target store and other businesses chose to close as well.