Authorities say that the owner did not take permission for the construction work. LUDHIANA: One person died, four others were injured after roof of the third floor of a factory collapsed in Baba Mukand Singh Nagar on Daba road on Monday morning. The authorities said that four workers were still trapped and efforts were on to rescue them. Police said that about forty workers were lifting the cemented roof of the third floor of an auto parts factory on when it collapsed. They added that about forty construction workers were trapped under the debris. Deputy Commissioner Varinder Sharma, who along with Ludhiana police commissioner Rakesh Aggarwal visited the spot, told the Times of India that NDRF, SDRF, police, municipal corporation, civil teams were carrying out rescue operations. He added that forty persons were believed to have been trapped under the debris of whom 36 were rescued.