Authorities in California rescued a man who was trapped inside a restaurant's grease vent for about two days.

Sheriffs and firefighters in Alameda County, California, received a call from a citizen claiming they heard a voice calling from help at a vacant Chinese food restaurant.

After tracing the voice to a roof vent atop the restaurant, authorities found a 29-year-old man trapped in a sheet metal grease duct, covered in grease and oil.

The man had been there for two days, the Alameda County Sheriff's Office said.

Firefighters pulled the man out of the duct after about an hour and transported him to a local hospital for dehydration.

Grease Vent
This image shows a man trapped inside the grease vent of a vacant restaurant. He was trapped for about two days before rescue.
Alameda County Sheriff's Office

"It is likely he wound not have survived another day given the circumstances," said the sheriff's office in a statement. "The suspect is expected to make a full recovery."

Authorities are conducting an investigation. The sheriff's office said they did not yet know whether the man intended to commit a burglary.

Follow Brett Molina on Twitter: @brettmolina23.