India, Jan. 30 -- The hoax bomb threats sent to 13 schools in Gurugram via emails on Wednesday were sent citing Haryana's water crisis and Khalistan referendum, said police on Thursday.

Investigators said that the same email was used also to send the hoax threats to a school in Karnal and Chandigarh on Wednesday. Officials said that a similar email to blow up the Punjab Secretariat in Chandigarh was sent on Thursday which also turned out to be a hoax after thorough checking.

Police officers said that the person who had sent the emails from the United States to Gurugram schools seems to be well versed with the water sharing dispute between Haryana and Punjab.

The suspect had written the email addressing Haryana chief minister Nayab Sing...