MALIBU (CBSLA.com) — A brush fire burned up to seven acres Friday along a Malibu hillside, but no structures were damaged.

Firefighters were sent to the area of Mulholland Highway and Kanan Road just before 1 p.m. as crews battled the flames with ground crews and two water-dropping helicopters.

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Flames were later seen on the hillside terrain, sending the fire to a second-alarm as additional crews and a fixed wing aircraft were called in for support.

Assistant Chief Anthony Williams of the Los Angeles County Fire Department says the cause was most likely accidental.

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“Could have been a number of things. Could have been a cigarette. Could have been a match. Could have been a discarded brake shoe. Somebody coming off Mulhollandm,” he said.

One firefighter reportedly suffered a minor leg injury when hit by a rock.

The blaze was about 70-percent contained as of 5 p.m.

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(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)