An accidental explosion ripped through an illegal fireworks factory in western India, killing at least 20 people, including 10 children, just days before one of India's biggest festivals. Police said that another 20 people were hurt after the explosion on Wednesday in the town of Deeg in the western state of Rajasthan, a senior police officer said. "We now have a death toll of 20 people, but it could rise as many are seriously injured," R. Narsimha Rao, a police inspector general in Rajasthan, told by telephone. The blast came only days before the Indian holiday of Diwali, or festival of lights, when millions of Indians take to the streets to let off fireworks. Months before Diwali, illegal fireworks factories spring up in many parts of India and almost all of these employ children, a child rights' group said. Poor children clandestinely work at these makeshift factories, which are often in people's homes, and almost every year there are fatal accidents. Police said an accidental fire caused the Wednesday blast inside the illegal factory. "The impact of the blast was huge and it brought down at least five houses in the area," Rao said. Rescue officials were trying to remove debris from the area to check if there were more survivors. "There could be more people trapped inside," Rao said, adding that a probe was underway to see how the illegal factory had sprung up in the area. Swapan Mukherjee of Free the Children India said the factories often hired children as "children come cheap," "We have come across cases where they are just given a meal a day for 18-20 hours of work, others are paid one fifth of a dollar,." There are at least 1,500 such illegal factories around each of India's major cities, Mukherjee said. Last year, four children died and dozens were hurt in a similar blast in West Bengal.