ABERDEEN, S.D. (AP) — Three people were hurt in an explosion at a South Dakota petroleum distributor. The explosion happened Monday afternoon in the truck maintenance shop of Harms Oil just west of Aberdeen. Co-owner Jason Harms confirms three people were hurt. Harms says all three were taken to a hospital. Harms says he’s unsure what caused the explosion. Traffic on nearby Highway 12 was blocked shortly after the explosion. Heavy smoke could be seen following the explosion. The explosion is under investigation.