ORANGE (CBSLA) — A brush fire burned through about 21 acres on Sunday afternoon inside Irvine Regional Park in Orange.

The fire, which started near 1 Irvine Park Road, was reported around 12:30 p.m., according to the Orange County Fire Authority.

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It grew from 1.5 acres to an estimated 21 acres, taking nearly 100 firefighters about an hour and a half to stop forward progress on the flames.

No injuries were reported, no structures were threatened and all animals inside the park were safe, fire officials said.

The cause of the fire has not yet been determined.

The park remains closed at this time as the investigation continues.

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(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)