Firefighters responded to a brush fire at Val Verde Park that reached three acres and continued burning Friday, fire officials said.

The Los Angeles County and Ventura County fire departments responded to the Castaic fire that started at 30300 Arlington Street at 5:07 p.m., Los Angeles County fire dispatch supervisor Art Marrujo said.

Firefighters did not know what caused the fire and were still putting out the flames just before 6 p.m., he said.