Seven people have been confirmed dead and over 200 others injured in an explosion in southwest China\'s Guizhou Province Tuesday, local authorities said. The accident happened at about 11:30 a.m., when two cargo trucks loaded with about 70 metric tons of explosives exploded in front of a motor vehicle testing station in the city of Fuquan, about 100 km from Guizhou\'s capital of Guiyang, according to the local rescue headquarters. Windows were shattered in nearby houses, and cars parked near the site were severely damaged. A nearby grain warehouse was seriously damaged as well. A witness told Xinhua that the testing station was destroyed and a neighboring five-story residential building was severely damaged. Police and rescue workers arrived at the scene swiftly after the blast occurred. Search and rescue operations are still under way More than 200 people have been rushed to a local hospital, 25 of whom are in critical condition, said a spokesman with the local rescue headquarters. The No. 1 People\'s Hospital in Fuquan received many of the injured, with some of them lying on beds in corridors due to overcrowding. Long Lifeng, a 40-year-old sales clerk at a nearby gas station, recalled that she heard a loud noise before passing out from the force of the blast. \"After hearing the noise, my head and legs were hit by flying objects, and then I fell unconscious,\" said Long, who later received four stitches on her head at the hospital. An investigation into the cause of the explosion is under way.