Updated at 6:11 p.m. ET: Michael Clarke Duncan, the hulking, prolific character actor whose dozens of films included an Oscar-nominated performance as a death row inmate in "The Green Mile" and such other box office hits as "Armageddon," "Planet of the Apes" and "Kung Fu Panda," is dead at age 54.

Duncan died Monday morning at Cedars-Sinai Medical Center in Los Angeles, where he was being treated for a heart attack, said his fiancée, Reverend Omarosa Manigault, in a statement released by publicist Joy Fehily.

The muscular, 6-foot-4 Duncan, a former bodyguard who turned to acting in his 30s, "suffered a myocardial infarction on July 13 and never fully recovered," the statement said. "Manigault is grateful for all of your prayers and asks for privacy at this time. Celebrations of his life, both private and public, will be announced at a later date." 

In the spring of 2012, Duncan had appeared in a video for PETA, the animal rights organization, in which he spoke of how much better he felt since becoming a vegetarian three years earlier. 

"I cleared out my refrigerator, about $5,000 worth of meat," he said. "I'm a lot healthier than I was when I was eating meat." 

Duncan had a handful of minor roles before "The Green Mile" brought him an Academy Award nomination for best supporting actor. The 1999 film, based on the Stephen King novel of the same name, starred Tom Hanks as a corrections officer at a penitentiary in the 1930s. Duncan played John Coffey, a convicted murderer with a surprisingly gentle demeanor and extraordinary healing powers. 

Warner Bros. / AP

Tom Hanks, left, Michael Clarke Duncan, center, and David Morse in "The Green Mile."

Duncan's performance caught on with critics and moviegoers and he quickly became a favorite in Hollywood, appearing in several films a year. He owed some of his good fortune to Bruce Willis, who recommended Duncan for "The Green Mile" after the two appeared together in "Armageddon." Clarke would work with Willis again in "Breakfast of Champions," "The Whole Nine Yards" and "Sin City." 

His industrial-sized build was suited for everything from superhero films ("Daredevil") to comedy ("Talledega Nights," "School for Scoundrels"). His gravelly baritone alone was good enough for several animated movies, including, "Kung Fu Panda," "Delgo" and "Brother Bear." Among Duncan's television credits: "The Apprentice," "The Finder," "Two and a Half Men" and "The Suite Life of Zack and Cody." 

Born in Chicago in 1957, Duncan was raised by a single mother whose resistance to his playing football led to his deciding he wanted to become an actor. But when his mother became ill, he dropped out of college, Alcorn State University, and worked as a ditch digger and bouncer to support her. By his mid-20s, he was in Los Angeles, where he looked for acting parts and became a bodyguard for Will Smith, Jamie Foxx and other stars. The murder of rapper Notorious B.I.G., for whom Duncan had been hired to protect before switching assignments, led him to quit his job and pursue acting full-time. 

Early film and television credits, when he was usually cast as a bodyguard or bouncer, included "Bulworth," "A Night at the Roxbury" and "The Players Club." 

WLEX

Carmike Cinemas in Lexington, Kentucky, were closed briefly due to a bomb threat Friday, but police gave the all-clear after a search turned up no explosives.

Law enforcement agencies across the country are responding to a bomb threat aimed at Columbus, Ga.-based Carmike Cinemas, which has 236 theaters in 35 states.

The threat was aimed at all the theaters showing "The Expendables 2," Carmike spokesman Terrell Mayton told NBC News. 

The threat was left in a phone message at the Carmike Cinema's corporate office Friday morning by a person identfying himself as a theater vendor, Mayton said.

The theater chain swiftly coordinated with local law-enforcement agencies, he said. None of the theaters was open for the day yet and heightened security measures will remain in place as they show movies, Mayton said.

"We're getting lots of calls and emails of 'all-clear,'" he said.

The Wilmington, N.C., Police Department cleared the scene on Cinema Drive after investigating a bomb threat, NBC station WECT reported. Officers walked through the building with employees, looking for anything suspicious. They did not find anything and reopened a road shut down during the investigation.

“Really the only prudent thing is to do the search. …Nothing was found,” police spokeswoman Lucy Crockett told the Wilmington Star News.

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Bomb-sniffing dogs searched the Carmike theaters in Lexington, Ky., but no explosives were found, NBC station WLEX confirmed.

NBCChicago.com showed aerial video of law enforcement agencies setting up outside a theater in Morris, Ill., southwest of Chicago.

On Thursday, Columbus police arrested an armed man who tried to sneak into a Carmike Cinemas theater pre-screening of “Expendables 2.” Joshua L. Vardeman, 23, faces three misdemeanor charges, according to the Columbus Ledger-Enquirer.

A federal investigator told NBC News the gunman and the bomb threat appear unrelated.

“Expendables 2,” which opened Friday, Sylvester Stallone and Arnold Schwarzenegger star in a sequel about bad-ass geezers with  Dolph Lundgren, Jean-Claude Van Damme, Chuck Norris, Jet Li, Jason Statham, Randy Couture, Terry Crews and Bruce Willis. In this one, the crew reunites for what they think is an easy paycheck, but when one of the team is murdered on the job, the quest for revenge puts them deep in enemy territory.

Review: “The Expendables 2” 

This story includes reporting by NBC News' chief justice correspondent Pete Williams and senior writer Jim Gold.

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WASHINGTON -- China has agreed to significantly improve market access for American movies, capping a weeklong visit by China's leader-in-waiting that led to billions of dollars in business deals, Vice President Joe Biden said Friday.

"This agreement with China will make it easier than ever before for U.S. studios and independent filmmakers to reach the fast-growing Chinese audience, supporting thousands of American jobs in and around the film industry," Biden said in a statement obtained by NBC News after Chinese Vice President Xi Jinping's whirlwind tour to the United States. "At the same time, Chinese audiences will have access to more of the finest films made anywhere in the world."

"U.S. studios and independent filmmakers cite China as one of their most important world markets, but barriers imposed by China and challenged by the United States in the WTO have artificially reduced the revenue U.S. film producers received from their movies in the Chinese market," said United States Trade Representative Ron Kirk. "This agreement will help to change that, boosting one of America's strongest export sectors in one of our largest export markets."

Pool / Getty Images

Chinese Vice President Xi Jinping, left, shows Vice President Joe Biden a chocolate-covered macadamia nut, given to him by Hawaii Gov. Neil Abercrombie, at the start of a meeting of Chinese and American governors Friday at Disney Hall in downtown Los Angeles.

On a global basis, films and other audiovisual services create a $12 billion trade surplus in the sector for the United States, the White House said.

Last year, Chinese box office revenue was up to $2.1 billion, with much of that from 3D titles.

The agreement allows more American exports to China of 3D, IMAX, and similar enhanced-format movies on favorable commercial terms, the U.S. Trade Representative's office said.

"This is a major step forward in spurring the growth of U.S. exports to China," Chris Dodd, president of the Motion Picture Association of America (MPAA), said in a statement.

"It has long been a top priority for the MPAA, and it is tremendous news for the millions of American workers and businesses whose jobs depend on the entertainment industry."

Walt Disney Co. president and CEO Robert Iger said in a statement obtained by The Hollywood Reporter: "China is one of the most populous countries in the world, and this agreement represents a significant opportunity to provide Chinese audiences increased access to our films."

The U.S. movie industry has long complained about China's tight restrictions on the number of foreign films allowed into the country each year, a limit that they say helps fuel demand for pirated DVDs that are widely available in China.

While the quota of 20 foreign films per year remains in place, Beijing granted other concessions that pleased Hollywood.

The deal strengthens the opportunities to distribute films through private enterprises rather than the state film monopoly, and ensures fairer compensation levels for U.S. blockbuster films distributed by Chinese state-owned enterprises, U.S. trade officials said.

The agreement will be reviewed after 5 years to ensure that it is working as envisioned, they said.

NBC News and Reuters contributed to this report.

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