An investigation is under way into what caused a stage to collapse, injuring several people during a Cheap Trick rock show in Ottawa, officials said. TMZ reported several Ottawa Bluesfest concertgoers were hospitalized following a severe thunderstorm that hit the show, causing the stage to fall apart moments after the band stopped playing 20 minutes into their act. The group said none of its members were hurt in the mishap. Neither the number of people injured nor the extent of their injuries was not immediately known.