ORINDA -- An Orinda resident who lit a cigarette while working with an unknown chemical outside his home Sunday afternoon was badly burned, police said.

Police and firefighters were called at 1:36 p.m. to 12 Orchard Road for a report that a man had been burned with some type of chemical, said Sgt. Howard Shiells.

A preliminary investigation revealed the man was using a substance believed to be paint thinner, lit the cigarette, then sustained serious burns to his hands while working outside of the home, Shiells said.

The man was transported to a local hospital to be treated for moderate-to-major injuries, police said.

The incident remained under investigation Sunday.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.