A father slammed his pickup truck into a bedroom where his newborn daughter and her teen mother slept, killing both before witnesses rushed to help free them from furniture and debris, police said Monday.

Police did not release the names of the victims or the 22-year-old driver but said his child was killed in the crash.

Eduardo Bonilla said the victims were his 19-year-old niece Trudy Bonilla and her 10-day-old child Naomi.

Trudy Bonilla and her ex-boyfriend argued over custody of the child only hours before the driver sped through a chain-link fence and crashed into the house late Sunday night in the Boyle Heights area, the uncle said.

"He was saying he was going to kill the daughter and the mom," Eduardo Bonilla said while standing in a yard near the crash site. "They had argued before, but nothing like that."

Police detained but have not yet booked the driver, who remained hospitalized with non life-threatening injuries.

Detectives said they were unsure whether the driver intentionally crashed into the house but noted there were no skid marks.

Trudy Bonilla's other 3-year-old son, who is unrelated to the driver, was in the room during the crash but was uninjured, family told The Associated Press.

Trudy Bonilla's uncle said the driver argued with her during a family reunion after she told him he could not visit their baby.

Two teenage witnesses walking home from a Halloween party said they ran to help after seeing the Cadillac Escalade speed down the street then open up an 8-foot hole in the wall of the residence about 11:45 p.m Sunday.

Teodore Romo said he tried to pull furniture off the victims, while his sister Katie went to check on the driver. She said he seemed to be in shock and just kept repeating, "Where's my daughter? Where's my daughter?"

More than half the truck ended up in the bedroom where the victims were sleeping, police Capt. Anita Ortega said.

A jagged hole remained in the wall Monday after the truck was removed, with foam insulation, piping and a broken air conditioner dangling from its edges. A stroller lay on its side in front of the sand-colored stucco house, along with toy cars, as shocked family members talked with each other in the next door neighbor's front yard.

Eduardo Bonilla said his niece was a happy mother who had just finished high school and wanted to go to college. The couple had dated for about a year and a half before breaking up three months ago, he said.

He said eight people lived in the home, which was deemed temporarily uninhabitable but expected to be fixed. He said 14 people attended the reunion on Halloween, but the only one hurt besides the woman and baby was a 17-year-old who was sent to the hospital with unknown injuries.

Ortega said there were no records of previous calls to the home.