LOS ANGELES — A mother is suspected of drowning her 1-year-old daughter and trying to drown the girl's 5-year-old sister, leaving that child hospitalized in grave condition, authorities say.

Lorna Valle was booked Wednesday night for murder and attempted murder and was being held on $1.5 million bail, Los Angeles police said.

The father of the children told police he found his wife trying to drown the girls in a bathtub in their South Los Angeles home after he returned from a grocery store, police Cmdr. Andrew Smith told the Los Angeles Times.

"The father stopped the mother," he said.

Firefighters answering a 911 call found the girls unconscious and not breathing in a converted garage behind a main house. They were in a bathtub and had no pulses, fire department spokesman Erik Scott said.

They were given cardiopulmonary resuscitation and taken to a hospital, he said.

Doctors worked on both girls for two hours, but 1-year-old Lindsay Taque died and the 5-year-old was transferred to another hospital in critical but stable condition, said Katreena Salgado, spokeswoman for California Hospital Medical Center. Los Angeles police later described her condition as grave.

Valle was taken into custody "because we believe she is responsible for this," Smith said.

Neighbors told the Times the family kept to themselves.

Valle seemed troubled "like she was disturbed," neighbor Jennifer Houston, 37, said.

"She stays in the house," said Judy McCann, who has lived on the street for about 30 years. "She never comes out."

A neighbor, Dina Cevallos, said she heard the father screaming.

"I asked him what happened. What happened?" she told KABC-TV. "And he said, 'you know, days ago (the mother) was in depression and I told her to go to a doctor and do something and she didn't want to do it.'"