A huge ventilator on top of the Mei Foo Sun Chuen block where nine people died in a blaze was being tested by firemen yesterday. They believe the ventilator, which was on during Tuesday's fire, might have fanned the smoke from its source on the sixth floor of Block Three, Phase Two, to the upper floors. Three of the dead were found on the 15th floor and four between the sixth and eighth floors - all died of smoke inhalation. The 36 injured have been discharged from hospital and police have started interviewing them to find out how they escaped. Yesterday, more than 19 warning letters were issued to the owners and management of residential and commercial buidings in Tai Po and Tsuen Wan for failing to keep fire prevention doors closed. The Social Welfare Department has so far contacted 27 families of the deceased and injured - 16 of which have requested welfare services such as financial assistance, counselling and clinical psychologist service. Burial grants totalling $32,100 have been given to the families of three people killed in the fire. A sum of $2,247 from the Li Po Chun Charitable Fund has also been granted to another family.