Moraga (KRON)  —  Fire crews battled a three-alarm vegetation fire in Moraga Thursday afternoon that had roughly burned 40 acres.

Firefighters responded around 12:30 p.m. to a grass fire near Natalie Drive which is close to the Compolindo High School and Soda Aquatic Center, fire Chief Stephen Healy said.

At 1:45 p.m. Healy said the fire was roughly 80 percent contained and he expected the fire would be completely contained within an hour.

According to the fire chief no structures have been damaged however one firefighter suffered minor injuries. Fire crews will be on the scene mopping up hot spots all night.

The cause of the fire is still under investigation.