It was a morning of mayhem on the Gov. Mario M. Cuomo Bridge. As many as 25 vehicles were involved in 10 crashes, leading to a pile-up that shuttered northbound lanes for roughly three hours as snow piled up on the new $3.9 billion bridge Wednesday morning. Rockland County officials said the chain reaction started around 9:30 a.m. when a woman exited her vehicle after a three-car fender bender and an approaching tractor trailer could not stop. The tractor trailer hit her car and pinned her against her car and the guard rail.