The bus overturned twice just before 5:30 p.m. Saturday in East Brunswick.
36 people were injured, including 17 children. All are said to be in stable condition at area hospitals.
The children and their adult chaperones were returning from a picnic in Millstone, sponsored by Newark Mayor Ras Baraka, who was not on board.
The cause of the crash is not yet clear.
Baraka said at a Saturday night news conference that early reports that the accident was caused by a hit and run involving a car were incorrect.
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