Students on two other buses on the field trip returned to the school Thursday morning and were reunited with their parents, said Paramus police Commissioner Holly Tedesco. "I can only describe it as horrific", Greenbaum said.
Greenbaum said he received an emergency response notification that people were possibly ejected in the crash, though he couldn't say from which vehicles.
It wasn't immediately known how many people were on the bus or in the truck.
The school bus was on its side on the median of Interstate 80 in Mount Olive with its front end sheared off.
A red dump truck with severe front end damage was also seen at the scene, about 50 miles outside of New York City.
At least two canine units were searching the woods along the roadside Thursday afternoon, but it wasn't clear why.
Police have responded to a serious accident involving a school bus and a dump truck in Mount Olive Township in Morris County, New Jersey, according to the township's mayor and a verified tweet from New Jersey State Police.
A spokeswoman for a local hospital told CNN that she believed two students had been admitted to St. Joseph's University Medical Center in Paterson, New Jersey. "The scene was as horrific as you thought it would be with a bus full of kids ripped off the frame", he said.
State police said an unknown number of children were on the bus.
About 10 victims were taken to St. Clare's Dover Hospital and St. Clare's Denville Hospital, according to Communications Director Patty Montgomery.
The school bus had markings for the Paramus School District.
The National Transportation Safety Board is gathering information on the crash, a spokesman said.
NBC 4 reported that an spokesperson confirmed that Morristown Medical Center was also receiving patients, but would not say how many. It's a popular spot for school trips.