PRAYAGARAJ, March 24 -- Four workers were killed and another 13 critically injured after a part of a cold storage facility collapsed in Prayagraj on Monday, police said, adding that efforts were on to rescue the dozens feared buried under the debris. Following the incident, ammonia gas began leaking from the facility, which fire brigade teams were working to contain, police added. Prime Minister Narendra Modi expressed grief over the loss of lives and announced an ex gratia of Rs.2 lakh each for the families of the deceased and Rs.50,000 for the injured from the PM's Relief Fund. Chief minister Yogi Adityanath also announced a Rs.2-lakh compensation for the families of the deceased and Rs.50,000 for the injured. The cause of mishap will be investigated later by a team of officials headed by ADM (Finance and Revenue) Vinita Singh. P6...