Police have arrested another teen on Thursday, the sixth suspect to be jailed in connection with the gang rape of a 15-year-old girl in Richmond, California.

Jose Carlos Montano, 18, was arrested on charges of felony rape, rape in concert with force, and penetration with a foreign object, said Richmond Police Lt. Mark Gagan. He is being held in lieu of $1.3 million bail.

Police said that as many as 10 people participated in raping and beating the girl in a dimly lit back alley at the high school, while another 10 people watched without calling 911.

Four other teenage suspects were arraigned Thursday on charges connected to the rape – Cody Ray Smith, described by the court as older than 14, pleaded not guilty to charges of rape with a foreign object and rape by force; Ari Morales and Marcelles James Peter also appeared with Smith, but did not enter a plea. The court described Morales as younger than 16, but did not give an age for Peter.

All three juveniles, who donned bulletproof vests at the hearing, were charged as adults.

The fourth person, Manuel Ortega, 19, appeared separately without an attorney and did not enter a plea. He did not wear a protective vest.