TEMPE, Ariz. (AP) — Authorities say three people were injured in a chemical explosion at a research lab on the Arizona State University campus in Tempe. Tempe Fire Department officials say Tuesday morning’s explosion was caused by chlorine dioxide, which resulted in a workbox becoming overpressurized. Phoenix radio station KTAR-FM reported that a third-party contractor was conducting a routine cleaning of the Biodesign Institute lab at the time. Authorities say three people were treated at the scene for skin lacerations. A 50-year-old man and a 27-year-old man were taken to a hospital with serious injuries that were not life-threatening.