The total amount of gold stolen is 7,821tola, according to the robbed jewellers. The jewellers' association said this is the biggest ever gold heist in the history of the country.

Two guards of a private security company, Security Management Services (SMS), in league with the burglars drugged two of their on-duty colleagues before breaking into the 16-storey shopping complex off Dhaka-Mymensingh highway, according to police and the owners of shops in the complex.

Angry shop owners took to the streets and blockaded the busy highway for over two hours yesterday protesting the heist and demanding immediate apprehension of the burglars.

The shop owners threatened greater movement if the burglars are not arrested within 24 hours.

"We may even announce programmes like laying siege to Bangabhaban if the people involved in the incident are not arrested immediately," said Anwar Hossain, president of Bangladesh Jewellery Manufacturers' and Exporters' Association.

According to local businessmen, the burglars entered the building soon after midnight after sedating with drugs security guard Monjurul Islam in the basement, and guard Salahuddin at the rear entrance on the ground floor. The shopping complex closed at 11:00pm.

Picking the locks on the collapsible gates at the stairs on the ground floor, they went up to the third floor with the lock picking kits. They bore a hole on the steel gate there using a flame gun.

Video footage recovered form close-circuit television camera (CCTV) recording shows five thieves cutting through the steel shutters, then the collapsible gates and the glass-doors of Parma Jewellers, Konica Jewellers, Preyoshi Jewellers and IK Jewellers with the flame gun.

The thieves used candles, torch lights and the flame gun to light the rooms during the heist.

"One of the thieves was wearing a protective jacket while cutting through the gates. They clearly appear very professional," Emran Chowdhury, owner of IK Jewellers, told The Daily Star.

The surveillance footage shows the burglars bagging the ornaments kept on the showcases at the display sections of all the four shops. After taking the ornaments, they threw the empty boxes on the floor.

The thieves emptied all the showcases of the shops and attempted to break four safes of IK Jewellers. They managed to break two, and looted the gold ornaments that were in the safes.

After looting the ornaments, the thieves broke the cashboxes of all the four shops and looted the money.

"It appears form the video footage that the thieves were holding candles and torch lights and also were using the light emitted from the flame gun during the robbery,"

According to the owners of the burglarized shops, the thieves made off with gold ornaments weighing about 2,450 tolas and Tk 1 lakh in cash from IK Jewellers, gold ornaments weighing 3,466 tola and Tk 2 lakh in cash from Konica Jewellers, gold ornaments of 1,205 tola and over Tk 1 lakh in cash from Parma Jewellers, and gold ornaments of 700 tola and Tk 1 lakh in cash from Preyoshi Jewellers. The heist that began at 12:14am continued till 3:30am.

The shop owners said although the whole incident was recorded on the CCTV tape, they could not identify the thieves because the images are hazy.

When security guard Kamal Hossain and his supervisor Mozammel Haq went to relieve guards Salahuddin and Monjurul of their duties at 5:45am, they found both of their colleagues lying unconscious.

"It seems the thieves dragged Salahuddin from the backside of the building to the main entrance and placed him in a way that he seemed to be sitting there totally conscious," said Mozammel.

On information, the owners of the shops rushed there and police rescued the two unconscious guards. Police recovered two screw drivers, a wrench, pliers, a pick, two empty bags and seven candles from the place.

Protesting the heist, shop owners and employees of Mascot Plaza kept their shutters down yesterday. They also brought out a procession and held a rally there before blockading Dhaka-Mymensingh highway in front of the market at 2:00pm. They vandalised four minibuses as well.

The blockade was withdrawn around 4:00pm after police and Rapid Action Battalion (Rab) intervened.

Police picked up security company SMS's manager, Sirajul Islam, for interrogation.

The shop owners said security guards Harun Mia and Enayet Kabir -- who have been missing since the incident -- were on duty from 10:00pm Tuesday to 6:00am yesterday.

The law enforcers could not arrest any of the burglars nor could they recover the looted gold or cash till filing of this report at 7:30pm yesterday.

Meanwhile, members of police, CID (Criminal Investigation Department) and Rab interrogated security guards Monjurul and Salahuddin.

"It is quite strange that no one could sense anything although the thieves continued the heist from 12:14am to 3:30am," said Anwar Hossain. He also demanded arrest of those responsible for planning security for the complex.

He said 29 jewellery shops have been burglarized in the city since 2001. In the second biggest heist, the thieves made off with gold ornaments weighing about 6000 tola from Karnaphuli Garden City in 2004. Gold ornaments of 4,500 tola were stolen from Navana Tower in Gulshan in 2005.

In a recent big incident, security guards of Holland Centre Shopping Complex at North Badda apparently helped burglars to steal ornaments, cellular phone sets, accessories, and cash worth over Tk 86 lakh on November 26 this year.