A strong 6.8 magnitude earthquake hit the mountainous northeast Indian state of Sikkim on Sunday, triggering tremors felt as far away as the capital New Delhi. The US Geological Survey said the epicentre of the quake, which struck at around 6:10pm (1240 GMT), was located just over 60 kilometres (40 miles) northwest of the state capital Gangtok. Telephone land lines to Gangtok were temporarily knocked out and mobile networks were quickly swamped, making communications with the affected area difficult. There were no immediate reports of any casualties or damage. Powerful tremors were felt in Guwahati, the main city in neighbouring Assam some 600 kilometres away, sending panicked residents running into the streets.