On 6th of january 2018 06:50 pm i was working on my laptop when all of a sudden there was a blackout due to power cut in our locality. i have a rooftop apartment. i got up from my desk and moved out on to the roof to look around the extent of power cut. it seemed that the power was out only for a few blocks around my building. there is a multi-storeyed building opposite to my vantage point. an unusual glowing red light attracted my attention over the terrace of the building. it appeared like warning lights for planes like the ones they have on tall towers. it did not make sense on such a low altitude. i kept looking. the light slowly started to ascend vertically up. it was quite dark and so i could only see the movement of the light. i thought somebody might be testing their drone cameras or something. didn't pay much heed. after rising a meter or so the light just went off, disappeared. since it looked unusual somehow, i took out my cell phone (motorola moto e2) and pointed its camera towards the sky. few seconds later it showed up in the sky at the same altitude but between my vantage point and the building where it appeared. it came quite close to my vantage point. hovered there for two to three seconds then disappeared momentarily and reappeared again just above the same spot where it disappeared. i thought to myself that a drone doesn't fly this quick. it went off again and then reappeared at a spot perpendicular and what appears to be 50 to 60 m apart from the last location. hovered there for a while and then disappeared again. i got it on my cell phone and kept pointing it towards the sky and waited for it to reappear. few seconds later it reappeared again above the building where i spotted it first hovered there for few seconds and then flashed a green light. after that it immediately descended and disappeared. i kept recording hoping it would show up again but it didn't. a minute or two later the power came back. i did come out later in the night to check whether i could spot it gain but to no avail.