MESA, Ariz. -- A mother of a patient at a suburban Phoenix children's hospital took her son's life before taking her own, police said Saturday.

Mesa police spokesman Steve Berry said nurses at Cardon Children's Medical Center in Mesa found the woman and her 5-year-old child dead inside the child's room while conducting a 2 a.m. bed check.

"It appears that the mother for unknown reasons took the life of the child and then took her own life there in the room." Berry said, according to CBS affiliate KPHO.

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They were later identified as 27-year-old Lola T. Griffith, or "Tammy," and her son Helious Griffith, KPHO reported.

The mother had a fatal gunshot wound, but it was too early in the investigation to release information about how the boy died, Berry said.

Upon finding the pair, the nurses immediately called for trauma units as well as security. An off-duty police officer was already working at the hospital, according to authorities.

Nobody at the hospital recalls hearing any gunshots or suspicious activity, Berry said. The boy was in a private room.

"Every two hours they do a check," Berry said. "They were seen alive and fine at midnight and then found at 2 a.m."

Police have completed their investigation of the scene and the room has been turned back over to the hospital.

No one else in the hospital was threatened or harmed.

A representative for the Banner Health system declined to comment when reached Saturday.

According to police, the boy had been hospitalized for the past week. Berry declined to say why the boy was hospitalized, citing privacy rules.

"I can tell you this family was actively involved with DCS (Arizona Department of Child Safety) and that it was an open case and that they were actively working on that as recently as two days ago," Berry told KPHO. "I'm told they had a family member with the mom, child and all the family members that were involved."