Dense fog and cold continue to disrupt normal life in several parts of north India. Three train accidents in Uttar Pradesh yesterday killed ten people and injured 40. Rail, road and air traffic continues to be affected in many parts. The railways have ordered an investigation into the accidents.<br/><br/>Large parts of North India, including Delhi, plunged back into darkness late last night as the regional electricity grid collapsed due to dense fog, hours after it was restored.<br/><br/>A senior official of Punjab State Electricity Board said in Chandigarh that the Northern grid has again collapsed, leading to disruption of power supply to all power plants in Punjab, Haryana and Chandigarh.<br/><br/>Several parts of the national capital also went without electricity late last night for the second time in a day following a major breakdown in the Northern grid.<br/><br/>A Delhi Transco official said the technical problem in the grid occurred at around 10 PM resulting in massive disruption of power supply.<br/><br/>Railway sources said, several long-distance trains, which left Delhi after 9.45 pm, were stranded in nearby areas due to lack of power supply.<br/><br/>Reports of power supply breakdown also came in from Jammu and Srinagar.<br/><br/>Earlier in the day, the fog led to the collapse of the the northern grid snapping power supply to vast tracts of north India, including Delhi.