ALHAMBRA, Calif. (AP) _ A 15-year-old student was apparently playing a joke when he accidentally hanged himself with a guitar strap in a school music room storage closet, police said.

Police were interviewing staff at Alhambra High School to determine if there was negligence in the death of sophomore Gregory Taggart, officers said Tuesday.

A teacher and other students were in the classroom at the time of last week's accident, police Sgt. Phil Sheridan said. He said the nature of the prank wasn't clear and the investigation wasn't over.

Sheridan said Taggart didn't intend to hurt himself.

Diana Taggart, the youth's mother, said her son was impulsive and was playing a practical joke. The teen had attention deficit disorder, she said.

``Sometimes they think things through, and sometimes they don't,'' she said.

The Alhambra School District is also investigating, spokeswoman Natalie Gaither said.