The Los Angeles Sheriff's Department is investigating why a man died after being taken into custody by Whittier police.
Whittier officers got the call Thursday afternoon when one of the man's relatives said he was suffering from a mental illness, and refused to get treatment.
Authorities said they found the man about a mile away from his home.
"The officers attempt to make contact," said Sheriff's Deputy Grace Medrano. "The male attempted to jump over a fence that led to a water reservoir. Officers did detain the male adult and handcuffed him."
At some point after he was handcuffed, the man lost consciousness. Officers began life-saving measures and he was transported to a local hospital. Authorities have not released the man's name or any additional details.