None of the victims have been identified.
The Sayreville woman was driving east on Bordentown Avenue about 2 p.m. on Tuesday when her car crossed into the westbound lane and struck an SUV, Sayreville police said.
The woman was in critical condition at Robert Wood Johnson University Hospital in New Brunswick.
A 7-year-old passenger in the SUV suffered lower leg injuries that are not considered life-threatening and was extricated by the Sayreville Fire Department, police aid.
The SUV's driver, a 27-year-old woman from Linden in Union County, and another passenger — a 1-year-old — also were taken to the hospital for evaluation, police said.
The crash took place near the intersection of Range Road and closed Bordentown Avenue for several hours.
Anyone with information is urged to call Sayreville Patrol Officer Tom Calise at 732-525-5430.
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