Officers responded to a call Sunday night of a man acting strangely, scaring customers and refusing to leave a Nation's Giant Hamburgers restaurant, the Oakland (Calif.) Tribune reported.
The officers encountered the man outside the restaurant and attempted to arrest him.
The man, in his early 30s, resisted and was subdued with a stun gun, police said.
Once handcuffed, his health immediately deteriorated and paramedics were called, taking the man to a local hospital where he was declared dead.
The cause of death had not been determined, police said, and the man's name was being withheld pending notification of his family.