The single vehicle accident happened at McKinley and Pine streets shortly in Passaic just before 4 p.m.
Emergency teams were examining the elementary-aged children, who all have wheelchairs, on the scene.
It did not appear there were any serious injuries.
Still, three of the children were taken to the hospital for evaluation, while the mother of the fourth signed a Refusal of Medical Assistance form at the scene.
The bus driver reportedly told police the brakes failed.
The investigation is ongoing.
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