Police said an unknown number of people began throwing rocks at a residence in the 1200 block of Santa Ines Way around 7:24 p.m.
Ronal Bonilla and a 16-year-old boy, both of Petaluma, exited the house with a baseball bat and knives and a physical confrontation ensued, Sgt. Marty Frye said.
Bonilla chased a male suspect and stabbed him in the arm causing a severe laceration. The juvenile then chased the suspects' silver late model Nissan Altima and struck it with a bat, Frye said. The rock-throwing suspects were gone when police arrived.
Police contacted Lesbia Valladares, 41, of Petaluma, as she left the scene with a baseball bat and knives, Frye said. Valladares refused to cooperate with police and she was arrested for obstructing an officer and concealing evidence. She was booked into the Sonoma County jail, Frye said.
Bonilla was arrested for assault with a deadly weapon, violation of probation and possession of burglary tools. He was booked under no bail in the county jail, Frye said.
The juvenile was booked into juvenile hall for assault with a deadly weapon, Frye said.
The suspect who was stabbed was taken to Petaluma Valley Hospital by a friend but was transferred to an undisclosed trauma center because he lost a lot of blood, Frye said.
Several of those involved in the incident are known gang members and police are asking anyone with information to call gang enforcement detectives at (707) 778-4477.