Rohtak Range Inspector General of Police V Kamaraj said the government railway police of Panipat had registered a case under section 152 for damaging railway property under the Indian Railways Act against the unidentified people.
Gandhi, 39, who travelled in a chair car (C-3), was safe, but one of the windowpanes in his compartment had cracked after being hit by a stone.
The police are probing all angles and investigating whether the incident was deliberate or another stray stone-throwing case, as questions have been raised if the security of the Gandhi family should be compromised in the austerity drive.
Kamaraj said broken glass pieces and some stones found in the train had been taken for forensic examination at the forensic laboratory at Madhuban in Karnal district. A few windowpanes in the five coaches were damaged, but no one was hurt.
Gandhi had boarded the train from Ludhiana.
"As the train was moving at a slow speed, the guard of the train reported to have seen three to four young men throwing stones at the coaches," Kamaraj said.
"We have identified the place where the incident happened."
Kamaraj said the guard told the police that the train was running slow near Anaj Mandi area of Gharaunda in Karnal district due to repair work on the tracks on the Karnal-Panipat section.
He said the guard has also shouted at the young men asking them not to pelt stones, but by then the window panes of some bogies had already been damaged.
The guard, Kamraj said, was in his cabin at the rear end of the train.
"The guard could not clearly see the faces of the miscreants in the darkness," the IGP said.
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