At least seven persons were killed and two went missing as typhoon Dianmu hit Vietnam, authorities said on Sunday.After making landfall in northern Vietnam on Friday, Dianmu weakened into a tropical depression, Xinhua news agency quoted the Natural Disaster Prevention and Control committee as saying.The typhoon left 695 houses damaged and 2,154 in urgent need of evacuation.Around 10,000 hectares of crops were flooded and 61 head of cattle and 1,895 poultry were killed, the committee said.The typhoon also swept away 14 bridges and damaged four dams.