Several teachers and students are in a critical condition after a school bus in the US state of New Jersey collided with a dump truck on a major highway.

A student and a teacher were killed and 43 others injured when the school bus with preteens on a field trip collided with the truck, ripping the bus apart and leaving students dangling by seat belts, officials say.

Governor Phil Murphy told reporters the crash occurred in the Mount Olive Township in northern New Jersey’s Morris County during an excursion to Waterloo Village, a restored 19th century canal town.

“Some patients are in critical condition and currently undergoing surgery, so please keep everybody in your prayers,” Governor Murphy said.

The bus, carrying 38 students aged between 10 and 11, and seven adults, were from East Brook Middle School.

“There is an awful lot we just don’t know,” he said, adding details of the crash were not being released pending an investigation.

The front end of the bus was severed from the vehicle and the body of the bus was separated from its chassis, which remained on the highway, while the dump truck remained largely intact.

“The bus flew off of the wheels, but it hit the metal thing on the side of the highway,” fifth-grader Theo Ancevski said.

He told reporters he escaped through an emergency door on the bus: 
”A lot of people (inside the bus) were screaming and they were like, hanging from their seat belts,” he added.

“The children were all over, outside,” said Morris County Office Of Emergency Management Director Jeff Paul.

“We had every injury type that you can imagine for a scenario like this. It’s tragic,” he told reporters.

Two other buses in the field trip convoy also carrying fifth-graders on the same trip returned to Paramus, officials said.

The operator of the dump truck, Mendez Trucking, had 33 units that drive 3.1 million km in total in 2017 and had been involved in seven crashes over the past two years, US Federal Motor Carrier Safety Administration records showed.

Company officials were not immediately available for comment.
The National Transportation Safety Board, which investigates accidents involving buses, was gathering information but was not investigating the collision, it said on Twitter.

-with AAP