LUCKNOW, India (AP) _ Rescuers searched through the wreckage of a packed express train for people trapped inside after it derailed in northern India on Sunday, killing at least 21 and injuring more than 100 others, officials said.

   The Kalka Mail train was on its way to Kalka, in the foothills of the Himalayas, from Howrah, a station near Kolkata in eastern India, when 12 coaches and the engine jumped the tracks near the town of Fatehpur in Uttar Pradesh state, senior railway official A.K. Jain said.

   The cause of the derailment was not immediately clear but it appeared that the driver applied the emergency brakes, Jain said.

   At least 21 people were killed and rescue workers pulled at least 100 injured passengers out of the wreckage, said Brij Lal, a state police official.

   The accident site was a pile of twisted metal. At least one coach flew above the roof of another ahead of it and was dangling precariously, television footage showed. Another coach was thrown away from the rest of the train.

   The toll was likely to rise as rescuers made their way through the coaches and used gas cutters to cut through the mangled metal, Lal said.

   ``We're trying to cut into the coaches and rescue those still trapped inside,'' Lal said.

   Medical personnel rushed to the area, about 75 miles (120 kilometers) southeast of Lucknow, the capital of Uttar Pradesh state.

   TV stations showed local residents helping injured passengers away from the train and breaking the windows of coaches to help those trapped inside.

   The number of passengers on board the Kalka Mail _ named for its past use in the postal service _ was not known. Express trains normally carry about 1,000 people and travel at speeds of 60-80 miles (100-130 kilometers) per hour.

   The derailment delayed several other trains, officials said.

   India's railroad network is one of the largest in the world and carries about 14 million passengers a day. Accidents are common, with most blamed on poor maintenance and human error.