At least seven people were killed as heavy rains lashed Hyderabad on Wednesday morning, officials said.The downpour brought the life in the city and outskirts to a standstill. Low-lying areas were inundated while traffic was thrown out of gear.As many as four children were among those killed in the incidents of wall or house collapse.A couple and their two children were killed when a boundary wall of a building fell on their hut in Ramanthapur area.In another incident in Bholakpur, a woman and her two daughters were killed when the roof of their house collapsed.Greater Hyderabad Municipal Corporation (GHMC) has opened a helpline and pressed its emergency squads into service to clear waterlogging.Busy roads have turned into cesspools with overflowing manholes and storm water drains.GHMC commissioner Janardhan Reddy appealed to people not to venture out of their houses.