I-5 shut down near Castaic as firefighters battle 50-acre blaze

CASTAIC, Calif. -- A 50-acre brush fire is burning along the side of the 5 Freeway north of Castaic, sending thick plumes of smoke into the air and resulting in a shutdown of the freeway.

Some structures may be threatened by the flames.

The Route Fire was reported just before 4 p.m. along the 5 Freeway near Templin Highway.

The CHP closed the southbound 5 at Vista del Lago Road and the northbound 5 at Templin Highway.

The fire was first estimated at 5 acres but spread to at least 50 in less than two hours.

DEVELOPING: This story will be updated.