Around 40 schools in Delhi received a bomb threat mail Monday morning with the sender demanding USD 30,000, a police official said.

The threat was sent in a single e-mail marked to the city's prominent schools including DPS RK Puram; GD Goenka, Paschim Vihar; The British School, Chanakyapuri; The Mother's International, Aurobindo Marg; Modern School, Mandi House; DPS Vasant Kunj; Delhi Police Public School, Safdarjung; DPS East of Kailash and Salwan Public Schools.

Most schools that received the threat suspended their classes and sent students back home as officials said.

A Delhi Fire Service (DFS) official said they received the first alerts about the bomb threats from DPS RK Puram (7.06 am) and GD Goenka Paschim Vihar (6.15 am).

He said bomb detection teams, fire officials, local police and dog squads responded immediately and conducted searches at the schools.

Nothing suspicious has been found yet, a police official said around 9.30 am.

He said said further operations are underway.

Sources said the email was delivered on the schools' id at 11.38 pm Sunday -- when the schools were closed -- from scottielanza@gmail.com.

"I planted multiple bombs inside the building. The bombs are small and hidden very well. It will not cause very much damage to the building, but many people will be injured when the bombs detonate," the email read.

It also said, "You all deserve to suffer and lose limbs. If I do not receive 30,000 dollar. The group =E2=80=9CKNR=E2=80=9D is behind this attack," it reads.

In a message to parents, Mother Mary's School, Mayur Vihar, said, "An email was received this morning regarding a bomb threat in school. As such, the students are being dispersed immediately as a precautionary measure. You are requested to kindly collect your wards from your respective bus stops.

While taking his daughter back from the school, Harish, one of the parents, told PTI Videos, "I received a message about emergency from the school. This is the failure of the government as the schools are getting such threats regularly."

In May, more than 200 schools, hospitals and other important government installations in the city received a similar kind of bomb threat but the case is yet to solved as the mail was sent using Virtual Private Network (VPN).