More than 30 schools in Delhi received bomb threats through e-mails on Tuesday, marking the second such alarming incident this week and the fifth within just nine days leaving students, staff, and authorities on edge in the National Capital.

According to police sources, more than 30 schools including The Indian School in South Delhi, Ambience Public School in Safdarjung Enclave, Dilshad Public School in Dilshad Garden and Crescent School in outer Delhi, reported that bomb threats were received by police authorities.

On Monday, around 20 schools including DPS RK Puram, Gyan Bharati School in Saket and Ryan International School in Vasant Kunj among others had received threat emails.

According to police sources, the contents of the letters are similar to the previous one and it is suspected to be sent by the same sender. The e-mail threatens to blow up the school if they do not receive one Million Dollars.

According to an official from the Delhi Fire Service (DFS), a call regarding a bomb threat was received from Crescent Public School in Saraswati Vihar. The official said that personnel from the fire department, local police, bomb detection team and dog squad conducted a search, but nothing suspicious was found so far. Some more schools have also received similar threat emails and checks are ongoing, the official added.

However, schools in Delhi-NCR switched to hybrid mode for conducting classes on Tuesday, following the re-imposition of anti-pollution measures under Stage-IV of the Graded Response Action Plan (GRAP). Under the revised GRAP schedule, classes for students in grades 6-9 and 11 in Delhi, Gurugram, Faridabad, Ghaziabad and Gautam Buddh Nagar must operate in hybrid mode (physical and online) under Stage-IV but students in classes 10 and 12 are required to attend school in person.

On December 14, eight schools, including the same DPS RK Puram, had received a similar email, in which the sender threatened to carry out an explosion using “bomb vests.”

Earlier, on December 13, about 30 schools received bomb threats via email, prompting a multi-agency search of their premises. At least 44 schools had received similar emails on December 9.

The Delhi Police Special Cell had registered an FIR in connection with the threat mail to 44 schools and initiated an investigation. Meanwhile, on December 14, the police said that they have identified a private school student as being responsible for sending a bomb threat email to a school in Paschim Vihar.

According to police, the student had sent the threat email to his own school, and after tracing the IP address, the police team traced his home. “Upon questioning, the child admitted to the act and was later counselled. He was let off with a warning to his parents to keep a watch on his behavior,” a senior officer said.