New Delhi, May 1 -- The anti-terror unit of Delhi Police has started investigations into the bomb threat email sent to over 130 schools in the Delhi-NCR region, as the initial probe hinted at a deeper conspiracy by a terror group during the Lok Sabha elections, officials said on Wednesday.

A case has been registered under relevant sections of law for offences like conspiracy and threat by the Special Cell and a dedicated team formed to conduct the investigation, an official said.

"The matter is related to national security. It needs a deeper probe," the official said.

In a scare of unprecedented scale, over 130 schools in the Delhi-NCR area received an identical bomb threat by email early Wednesday, triggering mass evacuations and sear...