Five men wielding fake guns barged into a multi-storeyed building here and whisked away the brother of Manipur’s chief minister N. Biren Singh and his assistant on Friday, police said.

Tongbran Lukhoi Singh, 43, who runs an NGO All-Women Child & Development in Manipur, his wife Ngangom Pushparani Devi and his assistant Moirangthem Shanta Singh, 42, were in their fourth-floor apartment in the township’s Action Area I when the the flat’s door bell rang, said an officer of the Bidhannagar Commissionerate.

The officer said Pushparani answered the door bell and the men introduced themselves as CBI officers. After entering the flat, they took away the trio’s mobile phones, the officer said.

They then asked Tongbran and his assistant to accompany them. “When the two asked why, they whipped out the guns and got them to walk into two waiting cars,” the officer added.

Soon after the men left, Pushparani received a Rs 15-lakh ransom call on her phone, the officer said. She then went to the New Town police station and lodged a complaint.

The cops scanned CCTV footage from cameras installed in New Town’s BA Block and identified the registration numbers of the cars.

“We sent the numbers to all police stations and traffic guards alerting them that they were being used for kidnapping. A detective department team also started tracking them down,” said a senior officer of the commissionerate.

After several hours, the police tracked down the vehicles near Park Street and both the men were rescued. The cops also arrested the five men, including Park Lane resident Vinod Rao, 32, Mohammed Riaz Ali, 32, who lives on Mirza Ghalib Street, Idris Ali, 33, Khairul Rahaman, 49, who hails from Topsia and Ballygunge resident Khumallambam Singh.

The cops seized a vehicle and three toy guns, along with some cash, from them. The other car could not be traced.