MARTINEZ -- Five suspected gang members and a teenage girl pleaded not guilty Wednesday to felony charges filed in connection with the Aug. 20 fatal shooting of a 16-year-old Oakley boy at an Antioch house party.

Police said Martin Navarro was shot because he was the ex-boyfriend of a young woman who was dating a member of the gang and because he associated with the gang's rivals.

Tony Martin, 19, 18-year-old Carlos Guzman, 19-year-old Leon Moreno, 18-year-old Ricky Mendoza and 21-year-old Christopher Donaldson are all charged with murder, conspiracy and gang participation. Navarro's ex-girlfriend, 18-year-old Jessica Juarez, is charged with being an accessory after the fact.

Martin is further charged with attempted murder for allegedly shooting a 17-year-old girl in the shoulder outside the party, and with murder and robbery in a separate case involving the killing of a 27-year-old man at a Concord park on Aug. 28.

A preliminary hearing for the defendants is scheduled for Jan. 17.

Contact Malaika Fraley at 925-234-1684. Follow her at Twitter.com/malaikafraley.