Comedian Tracy Morgan is in critical condition after a multiple-vehicle accident in New Jersey that left one dead.

The former “30 Rock” and “Saturday Night Live” star was traveling with six others in a limo bus on the New Jersey Turnpike when the accident occurred about 1 a.m. Saturday, said Sgt. Gregory Williams of the New Jersey State Police.

A preliminary police investigation found that a Wal-Mart tractor-trailer failed to notice slow-moving traffic and hit the back of the limo bus, which crashed into several other vehicles and overturned near Cranbury Township, NBC News reported. The driver “failed to observe slow-moving traffic ahead,” Williams said. “He observed at the last minute — just prior to impact — the limo bus carrying Morgan and his party.”

Comedy writer James McNair, 63, of New York, was killed, state police said. Four people, including Morgan, were taken to Robert Wood Johnson University Hospital in New Brunswick, N.J.

“His family is now with him and he is receiving excellent care,” said Lewis Kay, Morgan’s representative. “We don’t anticipate much of a change in his condition today but will provide a further update once more information becomes available.”

The 45-year-old actor’s assistant, Jeffrey Millea, and comedian Ardie Fuqua Jr. also were listed in critical condition, a hospital spokesman, Peter Haigney, told the Associated Press. A fifth passenger, comedian Harris Stanton, was treated and released. Two others were not injured.

In addition to the limo bus and truck, another tractor-trailer, an SUV and two cars also were involved in the accident, which closed the turnpike for more than five hours, AP said.

No charges have been filed and the investigation is ongoing, police said. The National Transportation Safety Board is sending a team to assist New Jersey State Police in the investigation, a spokesman told ABC News.

Morgan and his group had been traveling from a stand-up show at Dover Downs Hotel & Casino in Dover, Del., to New York. Morgan had been scheduled to perform Saturday night as part of his “Turn It Funny” tour at the Fillmore Charlotte in North Carolina. That show has been canceled, AP said.

The New York City native appeared on “SNL” for seven years before leaving for his own short-lived comedy, “The Tracy Morgan Show.” Morgan also starred as Tracy Jordan in NBC’s hit “30 Rock,” which ended in 2013.