Four people were killed in a suspected murder suicide at a home in Colorado over Halloween weekend.

Authorities were dispatched to the residence north of Colorado Springs just after 10am on Saturday after receiving a 911 call about a person who was seriously injured and in need of assistance.

Deputies with the El Paso County Sheriff’s office and several other local emergency agencies arrived to find two juveniles and two adults dead at the home.

The case is still under investigation but was described by the sheriff’s office as an “apparent murder/suicide” in a statement on Sunday.

The identities of the victims have not been released pending confirmation by the coroner’s office and notification of next of kin. It is unclear if the victims were related.

After the bodies were found, authorities issued a “reverse 911” alert advising residents within a two mile radius of the home to shelter inside with their doors and windows locked, FOX21News reported.

The alert was rescinded after investigators determined there was no ongoing threat to the community.

Residents of the quiet Sun Hills neighbourhood were startled by the massive law enforcement presence, according to The Gazette.

One resident named Joe said he heard sirens approaching and assumed there was a fire near by before he watched a large armoured vehicle pass his home.

“It felt like we were being invaded,” he told the newspaper.

Another resident who declined to give his name said he heard “Come to the front door with your hands up” blared through a loudspeaker after a tactical support unit arrived.

The sheriff’s office did not immediately return The Independent’s requests for comment on Monday morning.

Authorities have urged anyone with information about the case to contact the sheriff’s office at 719-520-6666.