SIMI VALLEY, Calif. (KABC) -- A fast-moving vegetation fire erupted on the hillsides above Simi Valley on Wednesday morning amid extreme red flag conditions, prompting evacuation orders and school closures as it spread to 170 acres.

The so-called Easy Fire began shortly after 6 a.m. near the 200 block of West Los Angeles Avenue. Homes in a nearby residential neighborhood appeared to be threatened by the flames, but the winds initially seemed to be blowing the fire in a direction away from houses.

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Mandatory evacuation orders were issued for an area bounded by Tierra Rejada to the north, Madera Street to the east, Olsen / Madera Street to the south and Highway 23 to the west, according to an alert from the Ventura County Fire Department.

An evacuation shelter was established at the Thousand Oaks Community Center at 2525 N. Moorpark Road.

MAP: Easy Fire evacuation zone

There were no immediate reports of injuries or structural damages.

The cause of the fire was unknown.

All schools in the Simi Valley and Moorpark unified school districts were closed Wednesday, according to a tweet from Simi Valley High School.

DEVELOPING: More details will be added to this report as they become available.