Siege after US gunman kills three in Pennsylvania

A suspected gunman in a series of deadly shootings in Pennsylvania has barricaded himself inside a home in neighbouring New Jersey, police said.

US police said the suspect shot three people dead in Falls Township on Saturday before fleeing across state lines to the home in nearby Trenton.

Residents were home when the suspect entered the house but they have since been safely evacuated, police added.

The gunman is believed to be a 26-year-old who was known to the victims.

The Bucks County District Attorney's Office in Philadelphia said that following the shootings, the suspect carjacked an individual at a dollar store before making his way to the home in Trenton, where he has barricaded himself.

Dramatic images captured the police response to the siege in Trenton, and appeared to show hostages climbing out a first floor window before being cared for by police.

The weapon used by the suspect is believed to be an AR-15-style assault rifle, officials told a news conference in Falls Township.

People related to the suspect are also understood to be among the victims in Falls Township, officials added.