Updated

A Northern California boy faced attempted murder and sexual assault charges Monday after police say he raped a 13-year-old girl and attacked her baby brother in their home.

Police said the young victims were home alone at the time of the break-in early Sunday in Vacaville.

The 14-year-old suspect allegedly raped and stabbed the girl more than 30 times. The 18-month-old infant awoke during the attack, prompting the boy to also stab him more than 10 times, police said.

The suspect is an acquaintance of the victims' older brother, said Mark Mazzaferro, a Vacaville city spokesman speaking on behalf of the police.

The victims' father, told KTVU-TV on Monday that his son was in juvenile hall at the time of the attack. The Associated Press is not naming the father to protect the identity of the girl, who is the alleged victim of a sex crime.

He said he and his ex-wife share joint custody of their children.

Sgt. Denise Quatman told the Vacaville Reporter newspaper that the 13-year-old girl showed "great courage" by somehow getting the suspect to fall asleep, allowing her an opportunity to grab her brother and escape to a neighbor's house and call 911.

The girl and her brother remain hospitalized in critical condition, but are expected to survive.

Quatman said a SWAT team found the male teen asleep in the victims' home and arrested him without incident. He was being held in the Solano County Juvenile Hall on suspicion of two counts of attempted murder and sexual assault.

Mazzaferro said police do not have a motive for the attacks as they were determining whether the teen entered by force or through an unlocked door.

The teen's mother told KCRA-TV in Sacramento, Calif., on Monday that her son is innocent.

The woman, whom KCRA did not name, said she believes her son is being framed by three other teens he snuck off with on Sunday morning.