An early morning fire broke out at Stony Hill Vineyard in St. Helena Sunday after a tree struck and downed a power line.

The quarter-acre fire began at 5 a.m. at the Upvalley vineyard, located at 3331 Highway 29 in St. Helena, according to Paul Duncan, CalFire fire chief.

No injuries were reported, said Duncan, and the vineyard was not harmed. Only vegetation was damaged, he said.

Fire crews from St. Helena, CalFire and Napa County Fire put out the last of the hot spots by late morning, said Duncan.

The cause of the fire is still under investigation, Duncan said, adding that power lines were down when crews arrived.

JD Guidi, news representative from PG&E, said the outage was caused by a tree falling into a power line.

“That is most likely what caused the fire, but we don’t know what caused the tree to hit the line,” he said.

Guidi said power was restored to the eight homes affected by the outage at 3:30 p.m.