The snowy mountains of Maine once again echoed with the roar of 900-horsepower off-road Pro 4 trucks as Red Bull Frozen Rush returned to the slopes of Sunday River Ski Resort. The raw power of these machines were put to the test by harsh winter conditions, as the trucks raced head-to-head over jumps, around gates and down ski slopes. The unique race will air on NBC on March 1 as part of the year-long Red Bull Signature Series.