A woman, 43, and a 23-year-old man were arrested in Glasgow on suspicion of conspiracy to commit fraud and money-laundering offences.
Some 300 mainly elderly people have been tricked out of money, police said.
Victims of the fraud are given "elaborate and convincing" reasons to withdraw cash which is then sent by taxi or courier.
The two latest victims, in Salisbury, Wiltshire, and Tiverton, Devon, lost £98,000. Other victims have been from the Wiltshire, Devon and Cornwall areas.
Properties were searched in the Castlemilk and Crosshill areas of Glasgow, a police spokesman said.
Officers seized a high-value car and a "significant" amount of money following the searches, officers said.
The spokesman said victims of the crimes in the Devon and Cornwall and Wiltshire police force areas had been duped out of about £2m by fraudsters since March.
They said the scam involves criminals phoning victims, who are normally elderly, and pretending to be a police officer.
The victims are then encouraged by the fraudster, who uses "elaborate and convincing" reasons to withdraw large sums of cash, which they are then asked to send to a destination by taxi or a courier, or by electronic transfer to another bank account.
Det Insp Tony Hubbard said he was worried the 300 police know about "may just be the tip of the iceberg" and that others may be "too embarrassed" to report they had been conned.
Two people have been arrested as part of an ongoing investigation into a £2m fraud in south-west England.