Andrew Pacheco, 21, and Aaron Bustos, 23, both of Fontana, were arrested Wednesday evening at Villa Motel in the 15200 block of Foothill Boulevard, Sgt. Robert Morris said.
Adrian Blanusa, 30, a known gang member with an arrest warrant from Los Angeles County and another case pending in Fontana, was already in custody at West Valley Detention Center in Rancho Cucamonga.
Morris said the man was shot in the head Dec. 15 in an apartment in the 8100 block of Wheeler Avenue.
Two days later, the wounded man was discovered in the apartment. He remains in serious condition.
The police investigation led officers to Blanusa. He was arrested Dec. 28.
Police have not identified a motive in the shooting, but records indicate all three men have been charged with robbery.
Blanusa has a pending court date in Fontana Superior Court on charges that he used someone's credit card or identity for burglary.
Pacheco's record indicates he has been arrested on suspicion of burglary, disorderly conduct and false representation to a peace officer.
Bustos has been previously arrested on suspicion of burglary, being a prisoner in possession of a weapon, disorderly conduct and carrying a dirk or dagger.
They were booked on suspicion of attempted murder, robbery, assault with a deadly weapon and participation in a criminal street gang.
Authorities ask anyone with information to call the Fontana Police Department at 909-350-7700.