FORT PIERRE, S.D. (AP) — The South Dakota State Fire Marshal’s Office continues it’s investigation of a house explosion that killed a baby and her grandparents and left two young children hospitalized with burns. A house about 11 miles southeast of Fort Pierre exploded around 10:20 a.m. Wednesday. Stanley County Sheriff Brad Rathbun says 6-month-old Harper Hupp and her grandmother, LaDonna Hupp, 61, died at the scene. William Hupp, 66, died at a hospital. Two boys, 5-year-old Myles and 3-year-old Royce, were seriously injured and flown to a burn unit at a St. Paul, Minnesota, hospital. The children’s parents, Kelsey and Trevor Hupp, were at work in Pierre at the time of the explosion. LaDonna and William Hupp were Trevor Hupp’s parents. Kelsey Hupp said on a Caring Bridge account Thursday that Myles has mostly first- and second-degree burns on 10% of his body and Royce suffered third-degree burns on 25% of his body on his chest and arms. A GoFundMe set up shortly after the blast has raised over 345-thousand dollars as of six-pm Thursday evening. A donation account has also been set up at First Dakota National Bank. Donations of clothing, food and other items are being collected at Maier Meats-The Hangout in Fort Pierre. Total Beauty in Fort Pierre is also accepting donations for the Hupp family. A benefit auction is also scheduled for June 10th at one pm at the Philip Livestock Auction. Donations in Huron are also being accepted at the Beadle County U-S-D-A Service Center.