Two cars collided in the westbound lanes of Route 22 near Adamsville Road just before 7 a.m.
One of the cars had to be cut open to rescue people inside.
One of the injured was rushed by medical helicopter to Robert Wood Johnson University Hospital in New Brunswick, two others were taken by ground to the hospital, and a fourth was taken to Somerset Medical Center in Somerville.
The westbound lanes of Route 22 near Route 287 were closed as emergency crews responded to the scene.
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