Collapse of old buildings and buildings catching fire in cities a major concern; this can be avoided if rules followed, says PM Modi at the All India Mayors' Conference. This comes as, the boundary wall of Jal Vayu Vihar society in Sector 21, Noida collapsed, as per reports. A few people are feared to be buried under the debris from the collapse. Drainage repair work that was ongoing near Jal Vayu Vihar in Sec 21 is suspected to be the cause behind the wall collapse, informed Noida DM Suhas LY.