A 9-year old boy was stabbed to death in Discovery Bay, and investigators are working on establishing a motive with the teen suspect in custody.

Authorities responded to a call just after 10 a.m. on the 1900 block of Frost Way in Discovery Bay, and by the time they arrived a family member had taken the 9-year old victim to the hospital where he was pronounced dead. Deputies thereafter sent out an alert that 18-year old William Schultz of Discovery Bay was the suspect.

ABC 7 reports that he was arrested at a hospital later in the afternoon and say that investigators are looking into mental health as a factor in the case.

Deputies have released no further details as they investigate the case.