California, USA (AP) — A woman disguised in scrubs was caught trying to steal a newborn girl from a Southern California hospital in a duffel bag after sensors attached to the baby alerted employees, Garden Grove police said.

The 48-year-old woman was arrested Monday at Garden Grove Medical Centre after a hospital staffer stopped her from leaving with the baby, Lieutenant Jeff Nightengale said during a news conference.

"At this point we don't have a solid reason why she stole the baby," Nightengale said.

The suspect is accused of posing as a nurse who came into the room of the baby's mother and told her to take a shower before a doctor came to examine her, Nightengale said.

Once the baby's mother was out of the room, the woman allegedly put the newborn in a duffel bag and tried to carry her out of the ward.

"An alarm went off when the baby crossed an imaginary line" in the hospital that set off a sensor, Nightengale said. He added that the baby was only in the duffel bag for a short period of time.

Nightengale credits an alert employee and hospital policies for stopping the suspect and saving the baby.

"The hospital staff reacted as they should," said Nightengale.

Monday's attempt may not have been the woman's first, and authorities are working with other law enforcement agencies to figure that out, Nightengale said.

The child wasn't harmed, and is back in the care of her mother.

Nightengale said the woman has no history of mental illness.