Los Angeles County Fire Dept. responded to a fire on Monday night in the 4400 block of Rockmere Way in La Cañada.

“The guesthouse in the back of the property was fully involved upon arrival of firefighters,” said Maria Grycan, LACoFD spokeswoman.

A man, about 70 years old, was found deceased inside the structure, Grycan said.

The cause of the fire has yet to be determined but is possibly electrical.

Due to the fatality, the Los Angeles County Sheriff’s Dept. Homicide Bureau is investigating.