Do not pass:

You should never pass if there is an oncoming vehicle in the passing lane, if your view is blocked by a curve or hill, at an intersection, before or on a railroad crossing or bridge, or in any other no passing zone. Unless you are on the opposite side of a multilane roadway with a median or shared center turn lane, you may not pass a stopped school bus that has its flashing red lights activated.
DMV Writen Test