New Delhi, Aug. 18 -- Police said they have seized digital video recording (DVR) systems from the neighbourhood of Patte Shah dargah near Humayun's Tomb, where seven people were killed after a wall collapse on Friday. The footage will help ascertain the sequence of events. Police are probing if the weak structure and lack of renovation caused the collapse. On Friday, the roof and walls of two rooms allegedly caved in due to heavy rains and waterlogging, trapping 11 people. Seven died-Swaroop Chand, 79; Mohammad Moin, 37; Anita Saini, 50; Mohammad Arif; Mohammad Abid; Meena Arora and her daughter Monushca. DCP (southeast) Hemant Tiwari said an FIR was registered against unidentified persons. "Some alleged that no renovation was done for 40-50 years. The walls had cracks and the base was weak due to waterlogging," said an officer. Police are checking records with Municipal Corporation of Delhi (MCD) and Archaeological Survey of India (ASI)....