Colorado officials say the gunman who killed six people in a mass shooting at a birthday party at the weekend was upset that he was not invited.

Iran Press/America: US Police say Teodoro Macias, 28, fatally shot his girlfriend, Sandra Ibarra-Perez, 28, and five relatives before turning the gun on himself.

The attack unfolded at the Canterbury Mobile Home Park in Colorado Springs early on Sunday.

The party was for three relatives, two of whom died.

The attack came less than two months after a mass shooting that left 11 dead at a grocery store in the north-central Colorado city of Boulder.

Investigators say the suspect who killed six adults, including his girlfriend, and took his own life in front of young children at a Colorado Springs birthday party over the weekend was fueled by jealousy after he was not invited to the family gathering. 219