Four people were rushed to the hospital Thursday night after a boat exploded while refueling at a marina near downtown on the Detroit River. The boat exploded about 6:55 p.m. at the Riverside Marina on the 11000 block of Freud. That's south of East Jefferson and west of Dickerson. Dave Fornell, deputy commissioner of the Detroit Fire Department, said two women and two men onboard suffered first- and second-degree burns and were taken to the hospital. A 27-year-old woman had first-degree burns on both feet. A 35-year-old woman had first- and second-degree burns on her right foot. A 50-year-old man had first- and second-degree burns on both calves. A 31-year-old man had first-degree burns on both calves. The cause of the explosion is still unknown and the boat is "pretty much screwed up," Fornell said.