Police have made an arrest in a shooting that killed two people in Denver New Year's Eve, including an 11-year-old girl.

Denver police say they have arrested 25-year-old Pedro Cortez at his home on investigation of two counts of first degree murder. They're not releasing any details on the motive but earlier said it was possible that the shooting could have been an accident, by someone celebrating the New Year.

Police say an 11-year-old girl and a woman were killed by a single bullet fired into a home from hundreds of yards just after midnight. Police say the pair were at a party with about 10 other people when at least one shot was fired from up to 300 yards away shortly after midnight.

One bullet went through the front wall of the house, passed through the head of the woman, who was seated, and struck the girl in the side.

Police spokesman Sonny Jackson says investigators traced the trajectory of the shot to determine that the bullet killed both victims. Police believe it may have been fired from the far side of a greenway and hiking trail adjacent to the house.

A second bullet was found in a snowbank in front of the home.