Do not assume the power company already knows about the downed line. Call 911 immediately. The sooner the power company knows about the problem, the quicker they can respond. Thunderstorms present their own unique set of problems and safety practices. The mast on an ENG unit is a lightning attractor.
Lightning is just as hazardous as power lines.
Resume work when the thunder storm passes and you can judge the storm to be three miles away in the opposite direction. Avoid solitary tall trees for shelter. Seek a fully-enclosed, all metal vehicle as a safe place. Remember, your remote vehicle with its mast up is not a safe haven. If lightning strikes anywhere close to the vehicle it's time for an immediate bail-out.