An explosion, possibly caused by an electrical short circuit, reduced to rubble a 20-feet-long stretch of a pavement in front of Stephen House, a stone’s throw from the BBD Bag bus stand, on Sunday evening.

There were no reports of injuries or casualties, an officer of Hare Street police station said. Being Sunday, the area was deserted when the explosion occurred.

Several cobblestones from the pavement landed on an electrical feeder box at least five feet high while some permanent reinforced concrete slabs on top of an underground utility chamber’s access pit were broken.

Stones and rubble from the blast landed on several stalls on the pavement that were closed.

Murlidhar Sharma, joint commissioner (crime), said a preliminary probe revealed that an electrical short circuit had led to the explosion.

“The area has subsided because of the explosion. We found no traces of explosives. It could be that an electrical short circuit in a CESC line caused the blast. Caretakers and guards of buildings in the area said they saw lights flicker, indicating a fluctuation in voltage,” said Sharma. “Forensic department officials will find out the exact cause of the explosion.”

Guards posted at a private bank branch and a telecom service provider store alerted the police on hearing a loud explosion around 5.30pm.

Sadhan Choudhury and Shankar Banerjee, the guards who called the police, said they initially thought that a portion of a building had collapsed.

“When we stepped out to check what had happened, we saw the area covered in smoke. In place of the concrete slabs over the pit, there was a huge crater,” said Chaudhury, who along with Banerjee ran towards the crossing to alert traffic policemen posted there.

A bomb detection and disposal unit and a dog squad arrived on the spot while a police team went around and asked guards at ATMs in the area to down shutters.

The police also called in engineers from the nearby construction site of Dalhousie Square station of East-West Metro to examine the pit. “We don’t have anything on this side of the pavement,” an engineer said.

CESC sent its engineers to the spot as well but an official of the power utility pointed out that there was no disruption

in supply in the immediate vicinity. Guards posted in the area said there was no power outage.