Colorado shooting suspect James Holmes (L) sits with public defender Tamara Brady during his first court appearance (Reuters)
James Holmes (left) sits with his public defender at a court hearing. Aurora, Colorado has now been rocked by a new shooting Reuters

Four people have died after a siege in Aurora, Colorado in which a gunman barricaded himself and three hostages into a house early Saturday morning. Reports suggest police used teargas in an attempt to force the gunman from the home where he had been holed up.

According to local NBC-affiliate KUSA-TV, the gunman was shot and killed when police and SWAT officers entered the dwelling at East Ithaca Place at around 08:30 am, after hours of negotiations proved futile. Police had first arrived on the scene when shots were fired at around 03:00 am, with investigators telling local outlets the three other victims - all adults - appeared to have been killed before the house was stormed.

Police Sgt. Cassidee Carlson said a SWAT team was called after gunshots were heard at the home, with the suspect then firing from the house approaching 08:15am. Carlson indicated a fifth person escaped uninjured, but would not go into details.

"We're just getting in there with our crime scene detectives, so obviously we'll have to determine if it was our rounds or his rounds," he said. "This is a big investigation, and a lot is entailed."

As of yet no names have been released, with authorities saying the motive for the killings remains unclear.

Local residents were evacuated and nearby roads closed as police attempted to end the standoff in the town which was also the scene of a mass shooting in July, when a gunman killed 12 and wounded 58 more at a screening of The Dark Knight Rises.

James Holmes, 25, is set to go on preliminary trial for that massacre in the coming days.