Surprise blast of rock, water and steam in Yellowstone sends dozens running for safety [Video]

A surprise eruption in Yellowstone National Park shot steam, water and dark-colored rock and dirt high into the sky Tuesday and sent sightseers running for safety.The hydrothermal explosion happened around 10 a.m. in Biscuit Basin, a collection of hot springs a couple miles north of the famous Old Faithful Geyser.Video posted online showed a couple dozen people watching from a boardwalk as the eruption sprayed and grew in front of them. As water and debris began to fall, they ran to keep clear, some yelling “Back up!” and “Holy cow!” People then turned to watch the spectacle under a huge cloud of steam.No injuries were reported, but the Biscuit Basin area was closed for visitor safety. The eruption damaged a boardwalk that keeps people off Yellowstone’s fragile and often dangerous geothermal areas.Vlada March was on a tour in the basin when her guide said something unusual was happening. March started …