Emergency vehicle lights at the scene of a traffic collisionInvestigators said an initial collision led to additional vehicles wrecking into one another.

MOBILE, Ala. — One person was taken to a hospital following a five-vehicle crash at the intersection of Old Shell and Cody roads in west Mobile, one of two wrecks Mobile police were investigating.

Investigators said the initial collision led to additional vehicles wrecking into one another, with five cars involved in total. The condition of the person transported was not immediately clear.

A second crash on McVay Drive

A separate crash affected traffic for a couple of hours on McVay Drive. It occurred in front of a new apartment complex and brought both directions of the roadway to a halt. Officers directed traffic while the scene was cleared.

Chain-reaction collisions

Multi-vehicle wrecks of the kind reported at Old Shell and Cody typically develop from a single initial impact, with following drivers unable to stop in time. Following distance and speed are the two variables that most often determine whether a two-car collision remains a two-car collision.

Old Shell Road carries substantial volume through west Mobile, and its intersections handle a mix of commuter, commercial and residential traffic. Crashes there frequently affect travel well beyond the immediate scene.

If you come upon a crash scene

Drivers approaching an active wreck should slow well in advance, move over when officers or emergency vehicles are present, and avoid stopping to observe. Secondary collisions at crash scenes are a persistent hazard, and they most often involve drivers who reduced speed too late.

Both incidents remained under investigation by the Mobile Police Department.