A 14-year-old boy remains in critical condition following a school bus crash on the Garden State Parkway in Bergen County on Monday night.

The crash happened at around 7:30 p.m. on the northbound side of the parkway just north of Exit 171 in Montvale, right before the James Gandolfini Service Area.

A New Jersey State Police spokesperson said it was a single-vehicle accident, with the bus veering of the road and flipping over. The bus was seen on its side facing the wrong way on the highway, and skid marks were visible on a nearby embankment. Investigators are still trying to figure out what caused the bus to topple over.

CBS News New York's Christine Sloan has learned the people on the bus were from a rabbinical school in Lakewood and were heading to New York to attend a post-wedding celebration.

"A 14-year-old boy is fighting for his life this morning after being pinned under the overturned bus on the Parkway," Montvale Mayor Mike Ghassali said in a social media post Tuesday morning.

Emergency crews from the Woodcliff Lake Fire Department and volunteers from the Montvale Fire Department were able to lift the bus and rescue the boy and get a pulse. He was then transported to The Valley Hospital in Paramus, according to Ghassali.

Officials said in addition to the critical 14-year-old, 13 of the 29 students on the bus, plus the 44-year-old driver, suffered minor injuries.

The accident stunned witnesses.

"I saw a head injury, like a lot of blood and stuff. It just did not look good. I'm praying for all the families and everybody involved," witness Liam Deacy said.

"Outside our window you could see somebody was being loaded onto an ambulance. It broke my heart," witness Laura Santacruz added.

Gov. Phil Murphy was briefed on the situation, and the crash drew a large response from first responders.