Story highlights Walmart says it believes truck driver complied with federal driving regulations

Tracy Morgan is still in critical but stable condition

Comedian James McNair, also known as "Jimmy Mack," died in the crash

Four other vehicles were involved in the crash

A truck driver charged in a weekend crash that killed a man and injured comedian Tracy Morgan and others in New Jersey was awake for more than 24 consecutive hours before the incident, a criminal complaint filed in the case says.

Kevin Roper, 35, is charged with vehicular homicide and assault by auto in the Saturday morning crash on the New Jersey Turnpike.

A Walmart spokeswoman issued a news release that said it was investigating the case.

"With regards to news reports that suggest Mr. Roper was working for 24 hours, it is our belief that Mr. Roper was operating within the federal hours of service regulations," Brooke Buchanan said in a written statement, referring to limits of 11 hours driving in a 14-hour period followed by 10 hours of rest.

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The wreck took place about 1 a.m. Saturday when the limo bus Morgan was in was hit by a tractor-trailer on the New Jersey Turnpike, police said.

The collision killed Morgan's fellow passenger, comedian James McNair, who performed under the name Jimmy Mack.

McNair's sister, Valerie Daniel, said he will be buried in a private ceremony on Thursday in Peekskill, New York.

Comedians Ardie Fuqua and Harris Stanton were among the injured, as was a man named Jeffrey Millea.

Morgan's publicist said Monday afternoon he is still in critical but stable condition.

His fiancee, Megan Wollover, is with him, publicist Lewis Kay said.

Morgan's injuries

Morgan suffered several injuries, including broken ribs, a broken nose, a broken leg and a broken femur.

Kay said Morgan underwent surgery on his leg on Sunday.

"We expect him to remain in the hospital for several weeks," he said.

The truck driver

The truck driver charged in the crash turned himself in to police, and was released on $50,000 bail Saturday night.

Truck driver Kevin Roper, 35, was charged with one count of death by auto and four counts of assault by auto.

Roper was a driver for Walmart.

"This is a tragedy, and we are profoundly sorry that one of our trucks was involved," Bill Simon, president and CEO of Walmart U.S., said in a statement.

"The facts are continuing to unfold. If it's determined that our truck caused the accident, Walmart will take full responsibility."

Chain-reaction crash

The wreck occurred on the turnpike in Mercer County, said Sgt. Gregory Williams of New Jersey State Police.

Photos: Tracy Morgan's comedy career Photos: Tracy Morgan's comedy career Actor Tracy Morgan returned to the stage to perform in October after recovering from injuries suffered in a six-vehicle accident in New Jersey in June 2014. The former "Saturday Night Live" cast member and "30 Rock" star was riding in a limo that was struck by a Walmart truck. Hide Caption 1 of 11 Photos: Tracy Morgan's comedy career Morgan got his start as a standup comedian, working at Harlem's Apollo Theater before landing his gig on "Saturday Night Live." He was a cast member from 1996 until 2003. In the October 3, 1998, "Big Bernard" skit, Morgan performed with basketball star Shaquille O'Neal. Hide Caption 2 of 11 Photos: Tracy Morgan's comedy career Tracy Morgan with Maya Rudolph in the "On The Subway" skit on April 13, 2002. Hide Caption 3 of 11 Photos: Tracy Morgan's comedy career In 2003, Morgan left SNL to start "The Tracy Morgan Show," but it ran for only one season before it was canceled. Hide Caption 4 of 11 Photos: Tracy Morgan's comedy career Morgan's acting career branched out from television to include movie titles such as "30 Years To Life." Director Vanessa Middleton, left, appeared with Allen Payne and Morgan at the premiere on March 27, 2002. Hide Caption 5 of 11 Photos: Tracy Morgan's comedy career Morgan and wife Sabina pose on the red carpet during the premiere of "Are We There Yet?" in Los Angeles in January 2005. The couple divorced in 2009 after 23 years of marriage. Hide Caption 6 of 11 Photos: Tracy Morgan's comedy career Morgan and Tina Fey worked together after SNL on the show "30 Rock." Morgan played Tracy Jordan, a character that was loosely based on himself. Hide Caption 7 of 11 Photos: Tracy Morgan's comedy career "30 Rock" cast members joke around with their award for outstanding comedy series backstage at the Emmy Awards in Los Angeles on September 21, 2008. Morgan was also nominated for outstanding supporting actor in a comedy series. Hide Caption 8 of 11 Photos: Tracy Morgan's comedy career Morgan starred with Bruce Willis in the 2010 movie "Cop Out." Hide Caption 9 of 11 Photos: Tracy Morgan's comedy career Morgan has stirred up controversy with some of his comments in his comedy acts. "I hurt people with this, so from the bottom of my heart I apologize to everybody who I offended with my words on stage," he said in 2011 after an anti-gay rant in one of his shows. Standup comedy should "heal people, not hurt." Hide Caption 10 of 11 Photos: Tracy Morgan's comedy career Tracy Morgan promotes his book "I Am The New Black" at Barnes & Noble Union Square on October 22, 2009, in New York. Hide Caption 11 of 11

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"The driver of the tractor-trailer failed to observe slow-moving traffic ahead," Williams said. "At the last minute, he swerved to try and avoid the Mercedes limo bus but struck it from behind, forcing the limo to rotate and overturn."

Four other vehicles were involved in the crash, the prosecutor's office said, but no one in those vehicles was injured.

Williams said he does not believe alcohol played a role in the crash, but that is under investigation.

The National Transportation Safety Board will investigate "safety issues related to commercial trucking and limousine safety," said agency spokesman Keith Holloway.

"All I know is I saw traffic ... and I stopped ... and I was upside down and in the vehicle," limo driver Tyrone Gale told WCAU

Gale suffered bruises in the crash, WCAU reported.

Christopher Thompson, the co-owner of Atlantic Transportation Services, which was operating the limo bus, said he thought the bus was heading to drop Morgan off in New Jersey.

From SNL to '30 Rock'

Morgan, 45, was a regular on "Saturday Night Live" for seven years. He later received an Emmy nomination for his role in the comedy series "30 Rock," in which he played Tracy Jordan, an exaggerated version of himself.

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The New York City native made his reputation with over-the-top characters and impressions of celebrities such as Mike Tyson and Oprah Winfrey.

Seth Meyers told CNN's "The Lead with Jake Tapper" that Morgan was a veteran of the "Saturday Night Live" cast when he joined in 2001.

Morgan "always looked out for me ... so yeah I'm definitely thinking of him now," said Meyers , now the host of "Late Night with Seth Meyers."

Morgan performed a comedy act Friday night at the Dover Downs Hotel & Casino in Dover, Delaware, the venue said.

Kay said Morgan's family "is tremendously overwhelmed and appreciative of the outpouring of love and support from his fans."