The accused had a database of around five lakh US citizens that included their names, contact numbers and some financial details which were used to target them and take them into confidence, they said. 

The raid was conducted at the call centre located in Sector 6, having a capacity of 150 desktops, around 5 pm on Wednesday over inputs of such illegal operations being carried out from a facility during night, deputy commissioner of police (Noida) Harish Chander said. 

"It's a large-size call centre. We have arrested 84 people, including women, from there. The centre functioned during night," Chander, flanked by additional DCP Shakti Mohan Avasthy and ACP Sushil Kumar, told reporters. 

"The call centre was used two to three times a week and in one night alone, the gang would make Rs 25 lakh to Rs 30 lakh. They had been operating for around four months now from the facility in Noida," the DCP said. 

Two key persons who are believed to be the masterminds behind this call centre have been identified but are at large, the officer said. 

The US embassy has also been informed about it, while formal communication with the Federal Bureau of Investigation and Interpol is being established, the police said. 

On the gang's modus operandi, Chander said they interacted with US citizens after contacting them using voice messages in which the callers would scare the gullible Americans by saying their 'social security number' -- a unique identity given by the government -- has been "compromised'. 

"The gang would then tell the US citizens that for assistance in fixing the problem, they should press 1 on their phones after which the call would land at their call centre (in Noida). Using a software, these people talked to them and shared their personal details, further convincing them that they are government officials," he said. -- PTI