Geyser eruption in Yellowstone national park sends visitors fleeing – video

A surprise hydrothermal explosion in Yellowstone national park has sent sightseers running for safety, after steam, rock and dirt shot high into the sky. No injuries were reported, but the Biscuit Basin area was closed for visitor safety after the falling rocks damaged a boardwalk that keeps people off Yellowstone's fragile and often dangerous geothermal areas.