The S-2 coach of the train suffered a structural failure causing a portion near the toilets to cave in, officials said. Toilet fittings including seats, fell onto the tracks as the coach body gave way, officials said.
No passenger was hurt in the incident, they said.
Passengers said they felt a sudden and violet jolt as the train started moving, prompting fears of derailment, following which several people rushed out immediately.
Railway officials and emergency teams reached the spot, evacuated passengers from the affected coach and detached it from the train.
Ludhiana Station Director Aditya said a replacement coach was attached to the train, allowing it to resume its journey to Katra without significant delay.Railways has ordered a detailed inquiry into the incident to ascertain the cause of the structural failure.
Deputy Superintendent of Police, Government Railway Police, Tejpal Singh said preliminary investigation had found no evidence of sabotage.
Officials believe a technical defect caused the coach body to fail at the start of movement.
Officers noted that the consequences could have been far more serious had the coach failure occurred while the train was running at high speed.