12 Bagnan: A major accident was averted when the alert guard of a Howrah–Kharagpur local spotted a large concrete slab lying dangerously close to the tracks as the train was passing through through Naopala village in Bagnan around 12.15 am on Monday.Acting on his information, RPF personnel, the senior section engineer and other railway staff rushed to the site.The slab was removed ensuring that train operations remained unaffected. South Eastern Railway authorities have ordered a high-level investigation to ascertain whether it was a deliberate act of sabotage.A week ago, stones were thrown at Shatabdi Express near SE Railway's Bauria station, injuring two passengers. A probe in underway into that incident.Bagnan: A major accident was averted when the alert guard of a Howrah–Kharagpur local spotted a large concrete slab lying dangerously close to the tracks as the train was passing through through Naopala village in Bagnan around 12.15 am on Monday.Acting on his information, RPF personnel, the senior section engineer and other railway staff rushed to the site.The slab was removed ensuring that train operations remained unaffected. South Eastern Railway authorities have ordered a high-level investigation to ascertain whether it was a deliberate act of sabotage.A week ago, stones were thrown at Shatabdi Express near SE Railway's Bauria station, injuring two passengers. A probe in underway into that incident.