Don't know what caused this crash. Professional drivers like the ones driving the bus and truck are usually very safe on the bridge. However, a lot of smaller cars drive really recklessly, far too fast and changing lanes with little warning. I drove over the bridge regularly back in the 1980s and even then, many drivers believed there was no police enforcement on the bridge because it spanned 2 counties. Really would not surprise me if a reckless small car driver cut off on the larger vehicles, causing a chain reaction crash.