In India's eastern state of Odisha, services have resumed on a stretch of railway where at least 275 people died Friday in a triple train crash.

The pileup occurred on a key line linking major cities in the country's east and south. The railways minister said the recovery operation is still underway.

Ashwini Vaishnaw said services are "moving toward normalization." He added that work to help those missing be returned to their families continues.

The minister said the crash was caused by a problem with the signal system.

Railway officials said an express train traveling south at over 120 kilometers per hour was wrongly switched to a loop line and collided with a stationary freight vehicle. Some of the derailed carriages then hit the rear of another express train traveling in the opposite direction.