Firefighters on Hawaii Island on Monday afternoon reponded to a brush fire on the Mamalahoa Highway that started around 3 p.m.. Witnesses say the brush fire was sparked when a large truck burst into flames on the shoulder lane of the highway. Police shut the highway down in both directions between Paauilo and Ookala near the 32-mile marker. Authorities have since reopened a single contraflow lane to traffic. The size of the fire is unknown, but police are asking drivers to steer clear of the area.