An accident involving an explosion Thursday night killed a stuntman on the set of an action movie starring and produced by Sylvester Stallone, MTV reports.

Another stuntman was seriously injured in the accident, and was reportedly in stable condition. The incident took place during shooting of the action sequel “The Expendables 2” in Bulgaria, the story reports.

The production company, Nu Image/Millennium Films, released a statement saying: "It is with great regret that we confirm this unfortunate accident. Our hearts go out to the families and those on the production affected by this tragedy. The filmmakers are working closely with the authorities in responding to and investigating this accident."

MTV reports: “The accident occurred while the second unit filmed at the Ognyanovo dam in Bulgaria. None of the film’s stars were present during the incident, as the first unit was filming at a resort more than two hours away.”

In addition to Stallone, the star-studded cast includes Bruce Willis, Arnold Schwarzenegger, Chuck Norris, Jean-Claude Van Damme and Jason Statham. The sequel brings back many cast members from the 2010 hit, which was written and directed by Stallone, the story notes.