While there were no casualties, the school's wall suffered damage.

Forensic teams and officers of the Delhi Police special cell have rushed to the spot and are trying to ascertain the cause of the blast.

A video recorded by a local resident showed a cloud of smoke billowing from near the blast site.

"I was at home. I heard a loud sound, saw a cloud of smoke and recorded the video. I do not know anything more. A police team and an ambulance have reached the spot," the eyewitness was quoted as saying by NDTV.

The blast took place near the CRPF school at Prashant Vihar at 7.47 am.

Senior police officer Amit Goel said they have called in experts to probe the cause of the blast.

In an update later, police said they had not found anything suspicious yet and were examining the underground sewage line as part of the probe.

Locals have said the explosion had shattered window panes of cars parked near the school and damaged the signboards of shops in the area

The National Security Guard has been informed and a team may visit the spot.