A Southern California woman was arrested Monday for tossing her seven-month-old son from the fourth floor of a Southern California hospital over a parking structure railing.

The mother was undergoing treatment for depression after the child was born with a physical deformity and she couldn’t accept his condition, her husband said. Sonia Hermosillo, 31, of La Habra was arrested Monday night at the Orange County Jail for the case of attempted murder.

She is being held without bail on an immigration hold and was placed on suicide watch. Hermosillo could make a court appearance as early as Wednesday, KTLA TV

However, the seven-month-old son is in extremely critical condition at the University of California, Irvine, Medical Center, and has a very less chances to survive, authorities said.

Sonia’s husband, Noe Medina, told The Orange County Register in an interview Tuesday that his wife had been hospitalized for postpartum depression in June after she said she didn't want their son, Noe Jr., who was diagnosed with congenital muscular torticollis - a twisting of the neck to one side.

The baby wore a helmet to correct his plagiocephaly, also known as flat-head syndrome. It was unknown if the infant had the helmet on when he was tossed over the railing.

Hermosillo and her husband have two daughters and the baby boy. According to neighbors, Hermosillo was a spirited and lovely mom with her girls.

She was very happy when she was pregnant with her baby, neighbor Sonia Herrera, 40, said.

But after the baby was born, Hermosillo changed suddenly and seemed depressed, Herrera said.

Medina told the Register that his wife didn't look at their son as normal and didn't accept that he was like this. Medina added that in recent weeks his wife seemed better and he began to trust her.

Hermosillo was not allowed to be alone with the baby while she was undergoing treatment. But she grabbed him Monday while Medina was watching their other two children.

A witness said that he'd seen a baby fall from the parking garage shortly after 6 p.m. He called 911 around 6:20 p.m. Using surveillance video, investigators focused on a 2000 Chevy Blazer that was seen leaving the garage minutes after the incident. The Blazer was linked to Hermosillo.

During the investigation, police had received a call from Medina reporting that his wife and son were missing. Hermosillo was arrested without incident when she returned to the scene a couple of hours later. She was cooperative with authorities, said police.

Police have not yet released a motive. Orange County court records indicate that Hermosillo has no major criminal record but pleaded guilty to four traffic violations in La Habra in 2008, including driving without a valid license and having no proof of insurance, reports the Associated Press.