As if the Internal Revenue Service weren’t scary enough, an “IRS impersonation scam” continues to target millions of senior citizens. Here’s how it works: Potential victims receive a phone call from someone purporting to be from the IRS. The caller claims the IRS has filed a lawsuit against them, and threatens to arrest them unless a payment is made immediately. The caller tries to coerce the victims into wiring money via MoneyGram, Walmart and other wire services.The U.S. Senate Special Committee on Aging estimates nearly 1 million Americans -- mostly senior citizens -- have been targeted, and 5,000 of them have lost a total of some $26 million last year alone.Republican Sen. Susan Collins chairs the Senate Committee on Aging.