Fire erupted from an upstairs bedroom at a Waterloo duplex after a mattress ignited Thursday night. The smoldering fire at 534-536 Western Ave. flashed over as firefighters entered the building. There were no injuries. The upstairs resident apparently caught the bed on fire around 7 p.m. Thursday, and he attempted to extinguish it by dousing it with snow scooped up from outside, said Battalion Chief Michael Moore with Waterloo Fire Rescue. When the snow didn’t work, he went to a neighbor to call 911. “Just seconds after we got here, the fire intensified and flashed out the window,” Moore said. “They were just making entry, started pulling the hose and that’s when it flashed.”