NEW BRUNSWICK, N.J. — Actor and comedian Tracy Morgan remained hospitalized as state and federal officials continued their investigation of a six-vehicle crash on the New Jersey Turnpike that took the life of a Morgan friend and left two others seriously injured, authorities say.

Morgan, 45, was in critical condition and his family arrived to be with him after a tractor-trailer rammed into his chauffeured limousine bus, carrying seven people, his spokesman Lewis Kay said. Morgan was “receiving excellent care,” the spokesman said.

A truck driver was charged with death by auto in the Saturday crash that killed comedian James McNair, described as a mentor to the former “Saturday Night Live” and “30 Rock” cast member.

Thirty-five-year-old Kevin Roper, of Jonesboro, Georgia, also faces four counts of assault by auto, Middlesex County prosecutors said. His bail was set at $50,000, and he was expected to turn himself in. It wasn’t immediately clear if he had an attorney.

Morgan and the group were traveling home from a standup comedy show in Delaware, officials said. About 1 a.m., near Cranbury Township, the tractor-trailer driver apparently failed to slow for traffic ahead and swerved at the last minute to avoid a crash, state police Sgt. 1st Class Greg Williams said.

Instead, the big rig smashed into the back of the Mercedes limo bus, prompting a chain-reaction crash with a second tractor-trailer, an SUV and two cars.

McNair, 62, of Peekskill, New York, who performed as Jimmy Mack, died when the limo overturned on the turnpike, Williams said. Morgan and Jeffrey Millea, 36, of Shelton, Connecticut, were flown from the accident scene to Robert Wood Johnson Hospital, where they were in critical condition, hospital spokesman Peter Haigney said.

A fourth passenger, comedian Ardie Fuqua Jr., was also in critical condition, while a fifth passenger, comic Harris Stanton, was treated and released, Haigney said. Two others in the limo were unhurt, including the driver.

The National Transportation Safety Board said it was working with state police to look at any issues in the crash related to commercial trucking and limousine safety.

Walmart President Bill Simon said in a statement a Walmart truck was involved and that the company “will take full responsibility” if authorities determine its truck caused the accident.

“We’re praying for the family and friends of the passenger who lost his life in the terrible accident” the statement said.

Morgan’s limo was owned by Atlantic Transportation Services, which said it had one employee behind the wheel and a second in the front passenger seat.

“Although the investigation is still pending, we concur with the preliminary reports that the accident was caused by another vehicle traveling behind the Atlantic limo bus,” the Rehoboth Beach, Delaware-based company said.

Morgan performed comedy standup Friday night at Dover Downs Hotel & Casino. His scheduled appearance at the Fillmore Charlotte in North Carolina on Saturday was canceled.

Fuqua had tweeted that he was opening for Morgan on Friday. On his Instagram page, Fuqua included a collage of photos from the Delaware show.

“This is what it looks like from the stage to see a standing ovation from 1500 people,” Fuqua wrote at around midnight Friday. “Then we traveled back to NYC in style in a luxury Mercedes Sprinter. Road life is a good life!”

McNair was a close friend and mentor to Morgan, Morgan’s ex-wife, Sabina Morgan, told the New York Daily News. “He was one of the first comedians that took Tracy under his wing,” she said. “They were very close.”

Royale Watkins, a Los Angeles-based comedian who said he had performed in New York clubs with Morgan and McNair, described McNair as having a big personality.

“There may be guys like Tracy who get the fame and notoriety, but you have people like Jimmy Mack who have kind of energized and fueled cats like Tracy and kept them going on the road,” Watkins said.

Morgan, a New York City native, joined “SNL” in 1996 and left to star in “The Tracy Morgan Show” in 2003. That show lasted just one season. In 2006, Morgan found a long-running role on NBC’s hit show “30 Rock,” which was created by “SNL” co-star Tina Fey. He received an Emmy nomination for best supporting actor for “30 Rock” in 2009.