and just saw a lot of chaos and devastation. >> reporter: rescue workers using ladders to get inside the bus, looking for any injured passengers. more than 40 people rushed to nearby hospitals. the ntsb launching a go team to investigation. the interstate temporarily shut down. traffic backed up as far as the eye can see. clayton sandell, abc news, denver. >> clayton sandell with those devastating images tonight. all right, clayton, thank you. also developing tonight, the explosion and the desperate rescue effort in chicago. workers trapped by a suspected methane blast at a water plant. at least ten people hurt. firefighters climbing through debris, searching for victims buried deep when the roof collapsed on top of them. abc's alex perez is at the scene tonight. >> reporter: just before 11:00 a.m., an explosion reported at this water purification plant in chicago. a huge portion of the roof collapsing. ten employees buried in the rubble. >> we got a total collapse of the structure. we have multiple victims trapped.