Multiple fire agencies are actively working to extinguish a brush fire that started Saturday night on an island off Highway 361, between Newport Pass and Zahn Road.The fire is believed to have started around 9 p.m. and has burned at least 50 acres so far. Firefighters from Corpus Christi Fire, Aransas Pass Fire, and Flour Bluff Fire are on the scene attempting to contain the blaze. According to Corpus Christi Assistant Fire Chief Bill Belyue, as of 12:20 a.m., the fire has still not been contained.Police on the scene are actively investigating the cause of the fire. Belyue told KRIS 6 that they cannot confirm reports that fireworks are to blame.Belyue strongly encourages drivers to avoid Highway 361 and Zahn Road for the time being. He also explained that the fire is sufficiently controlled that property near the fire should remain untouched, but fire crews remain vigilant. For the latest local news updates, click here, or download the KRIS 6 News App.