A man was arrested on suspicion of stabbing his co-worker's 3-year-old daughter to death in Los Angeles on Monday.

The woman picked her child up from daycare and brought her to a garment factory where she worked.

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When the woman stepped away from her work station, the Los Angeles Police Department said a co-worker started stabbing the girl without warning. The girl, known as "Baby Ruby," died at a hospital.

The child was taken to the hospital, where she later died.

Ricardo Augusto Utuy, 34, was arrested on a murder charge. The motive is still unclear.

Police told the Los Angeles Times that witnesses reported that the man would talk and laugh to himself. Witnesses told KNBC that Utuy was newly hired.

The Associated Press contributed to this report.

Click here for more from the Los Angeles Times.