PORTLAND, Ore. -- An adult and three minors charged in the death of an Oregon teenager have pleaded not guilty to murder.

Police arrested 20-year-old Isai Guzman-Ramirez, 15-year-old Obed Garcia and brothers Cristian Martinez-Chavez, 17, and Francisco Martinez-Chavez, 16, on Saturday after 17-year-old Jose Ricardo Morales was found dead on a Gresham sidewalk. He had been shot with a .22 caliber rifle.

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According to court documents, the shooting stemmed from a dispute earlier in the evening in which Morales ran up to a vehicle and punched one of the teens in the face.

Court documents say at least two of the defendants are gang members.

The shooting, at the intersection of Southeast 187th Avenue and Southeast Stark Street, was reported to Gresham Police at 10:40 p.m.

The East County Major Crimes Team is investigating. Anyone with information about the homicide is asked to call the Gresham Police at 503-618-2719.