The drone-like objects spotted in Calcutta’s night sky on Monday had not flown over military installations at Fort William, now known as Vijay Durg, officials of the army’s Eastern Command said on Wednesday.

All of them were spotted in civilian areas, they said.

“The drones that are being talked about were all spotted in the civilian areas of Maidan and none over the military installations,” a senior army officer of the Eastern Command said on Thursday.

“The army is continuing with the probe into the incident based on the inputs shared by Kolkata Police,” he said.

Around 10.30pm on Monday, several flying objects resembling drones were allegedly spotted near Fort William and in central Calcutta.

Senior police officers said they received reports from people saying that unmanned aerial objects were spotted flying past Vidyasagar Setu, Hastings, Rabindra Sadan, Victoria Memorial, Fort William, and moving towards The 42, the skyscraper on Chowringhee Road.

Police have initiated a probe into the sighting, and so has the army’s Eastern Command.

Sources said those who reported the flying objects on Monday night said they probably flew into Calcutta from parts of Mahestala and Behala on the city’s southern fringes.

Eyewitnesses said these hovered in the sky for nearly 20 minutes.

“The objects flew over areas under the jurisdictions of three police stations, including Maidan, Shakespeare Sarani and Hastings,” the officer said.

An alert has been sounded across all divisions of the city police.

Sources in the eastern command said the army was equipped to handle drones flying over the headquarters without the necessary clearances, including “neutralising” unmanned aerial objects with short-range air defence systems.