Mumbai, July 7 (NDTV): A drone that flew around the Bhabha Atomic Research Centre near Mumbai, causing a security scare, was allegedly operated by employees of a real estate website.

A professor who works at a college nearby noticed the drone on Monday and filmed it on his cellphone. He has submitted the footage to the local police. A group of people who operated the drone can reportedly be seen leaving the location in a car.

A case has not yet been registered. Police are questioning the people who were allegedly flying drones. Flying any object over the city is illegal unless police permission has been granted.

The Bhabha Atomic Research Centre, which includes advanced nuclear labs, has been on a terror hit list for years.

In May, a high alert was triggered at the main international airport in Mumbai after a pilot reported a sighting of "mysterious objects" floating above the runway. They were later identified by the police as helium balloons released as a marketing stunt for a diamond-selling company.