The accident happened at 10:21 (1421 GMT) in Mount Olive, about 50 miles (80 kilometers) west of New York. The bus had been taking the school children to Waterloo village on a class outdoor education trip.
There were 45 people on board — seven adults and 38 students. Two were killed and the other 43 were taken to hospital, some of them critically injured and undergoing surgery, New Jersey Governor Phil Murphy said.
The bus was one of three transporting fifth graders from East Brook Middle School in Paramus on the class trip.
“We are devastated by today’s event,” Paramus public school superintendent Michele Robinson told a news conference.
The precise cause of the accident was not immediately clear.
The driver of the dump truck, with which the school bus collided, was also in hospital, officials said.
