A blast wounded 13 people in Thailand's capital early Thursday when assailants hurled an explosive device at market vendors who had gathered to protest a rent hike at the government-owned facility, police said. The blast occurred in the Thai capital at around 1 a.m. local time when some protesters were sleeping in makeshift tents while others gathered outdoors, Pol. Col. Sutip Palitkusontap said. Twelve of the injured were hospitalized, two of them with serious injuries, he said. Hundreds of vendors who operate stalls at the outdoor market have been staging a protest against the facility's new privately contracted management company since Wednesday afternoon, Sutip said. There was no claim of responsibility for the attack and no indication that the blast was related to Thailand's continuing political strife, which has included protesters camping out outside the prime minister's offices.