MARTINEZ (KRON) – Fire officials say a brush fire is burning out of control in Martinez near Highway 4 on Friday afternoon.

The fire was first reported at 12:10 p.m. in Franklin Canyon, according to officials.

Contra Costa Fire PIO Steve Hill says homes in Franklin Canyon are being threatened by the fire.

Hill says the fire is now burning up to five to six acres.

Officials do not know the exact cause of the fire, however, an investigation is underway.

Con Fire is on scene of 5-6 acre wildfire burning in the vicinity of 2700 Franklin Canyon Road, Martinez. Structures are threatened. Multiple resources are on scene and enroute, including Cal Fire air tankers. Please avoid the area to allow first responders access. #fellowic — Con Fire PIO (@ContraCostaFire) July 5, 2019

Check back for more details as this is a developing story.