A fire on the fifth floor of a 10-storey residential-cum commercial building on Saturday afternoon left AJC Bose Road flyover-bound traffic from the Parama flyover crawling for some time as firefighters took their position on the flyover.

The fire was detected around 2.40pm when some eyewitnesses spotted thick black fumes rising from a fifth-floor window with several air-conditioning units just beneath it.

The building, Krishna, stands at the intersection of AJC Bose Road and Ballygunge Circular Road and houses several offices and commercial establishments, including a car showroom, on the ground floor.

Eyewitnesses said several employees from the offices located in the building had stepped out for lunch.

Those inside began scrambling down the stairs as fire alarm bells kept going off. Fumes gushed upwards and glass panels crashing down.

With flames leaping out of a fifth-floor window that opens towards the flyover, the firefighters decided to spray water jets from the Red Road-bound flank of the AJC Bose Road flyover, forcing traffic to move in a single lane on a stretch for some time.

Officers of the fire and emergency services department said they decided to take a 360-degree approach, and hence some fire tenders were on the flyover, while others worked from the ground.

Police said seven fire tenders brought the blaze under control within an hour. No one was trapped or injured, even though some offices and shops were open.

“The seat of fire was inside a room on the fifth floor. Fire tenders worked from the top and beneath the AJC Bose Road flyover to ensure that the fire did not spread because of the wind,” said an official of the fire and emergency services department.

“The power supply was snapped, and those on the floors immediately below and above the seat of fire were evacuated.”

The police said several offices inside the building were closed because it was a Saturday.

Those who were inside covered their faces with towels and handkerchiefs as black fumes engulfed the building and flames leaped out.

“It appears to be because of a short-circuit. The room has been sealed, and we expect forensic experts to examine the spot and identify the cause of the fire,” a senior officer of Karaya police station said.