Three people were killed and a fourth was injured in a shooting in Mukilteo, Washington north of Seattle, according to police. About 15-20 people were partying at home in the Chennault Beach neighborhood when gunfire broke out around 12:30 a.m., according to Mukilteo Police, NBC station KING5 reported. No other details about ages of the victims or what was happening in moments leading up to the shooting have been released.