MARSHALLTOWN, Iowa-- Heavy rain this week's being blamed for a Marshalltown building collapse. The Marshalltown Fire Department says the vacant building wasn't stable, and the weight of the rain water on the roof caused one of it's walls to come down early Wednesday morning. Fire Chief David Rierson says crews decided to demolish the rest of the building for safety reasons. He tells WHO-TV it's unknown if the building was affected by last summer's tornado.