New Delhi, Nov 19: Four people were killed on Monday as a massive fire enveloped an illegal factory here, an official said, adding that its owner had been arrested.The Delhi Fire Service said the blaze was reported from Karol Bagh's Beadonpura area at around 12.20 p.m."The victims were brought out of the factory. They died before reaching the hospital," the official said, adding that one person who was injured was being treated."Initial probe has suggested that the fire originated due to the use of steam press.""During the investigation, it was found that the factory was being illegally run by one Ajay Khurana. He was later arrested from his residence," APRO of Delhi Police Anil Mittal said.