More than 10 Delhi schools received bomb threat on Monday, police said, marking the fourth such instance of threat emails mentioning schools in past eight days in the national capital.

According to a Delhi Police source, the fire department, bomb detection team and dog squad searched the school premises but nothing suspicious was found.

On December 14, eight schools, including DPS RK Puram, had received the similar kind of mail, with the sender threatening to trigger blasts with "bomb vests".

The source said the contents of the letters is similar to the previous one and it is suspected to be sent by the same sender. On December 13, about 30 schools received bomb threats over email, triggering a multi-agency search.

Before that, at least 44 schools received threat emails on December 9.

The Delhi Police Special Cell had registered an FIR in connection with threat mail to 44 schools and started the probe.

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