US President Barack Obama has warned that flooding and power cuts are still a risk as tropical storm Irene moves north, towards Canada. The storm, downgraded from a hurricane, passed New York on Sunday but Mr Obama said, the danger was not yet over as swollen rivers could burst their banks. More than 300,000 people evacuated from low-lying areas in New York City, are being allowed back home. The storm has killed at least 21 people and caused extensive damage.Reports say in New York that Irene threatened 65 million people along the US east coast, which is considered as the largest number of Americans ever affected by a single storm. Widespread flooding is reported in Vermont where hundreds of people have been told to leave the capital, Montpelier.