The Hulk is on the move in Johannesburg. Bruce Banner's (Mark Ruffalo) angry alter ego is spending some time in South Africa while The Avengers: Age of Ultron crew shoots the film's opening sequence, and the giant green monster is making a mess.

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Thanks to the wonders of CGI, Ruffalo doesn't actually need to be on set for the Avengers first international pit stop, but the actor did chime in about his character's current path of destruction.

"Sorry for the mess," Ruffalo tweeted on Tuesday. "I can keep a lid in it usually but when I blow it's bad."

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'Bad' is a bit of an understatement. Johannesburg is playing host to Marvel film crews for two weeks, and curious bystanders are busy documenting the 'Hulk Smash!' rampage via Instagram. New videos show innocent civilians fleeing the scene as an invisible force flips cars and ignores the constant barrage of police gunfire (see videos below).

Meanwhile, director Joss Whedon is currently preparing Ruffalo and his costars for filming at Shepperton Studios in England.

The Avengers: Age of Ultron will hit theaters on May 1, 2015. Scarlett Johansson (Black Widow), Chris Hemsworth (Thor), Chris Evans (Captain America), Robert Downey Jr. (Iron Man), Jeremy Renner (Hawkeye), Aaron Taylor-Johnson (Quicksilver), Elizabeth Olsen (Scarlett Witch), and James Spader (Ultron) will star alongside Ruffalo.