Fire crews responding to a fire call at Mercier Grapevine Nursery in Vacaville made a disturbing discovery this morning. 

Fire crews responded to a call about 3:30 a.m., and upon arrival found a burned body, according to the Solano County Sheriff's Department. 

The incident is being treated as a criminal investigation.

All employees at the nursery are being questioned.

The fire appears to have started in a shed used to store tractors.