HOUSTON -- It's one of the most common e-mail and traditional mail scams out there. It's called the Nigerian scam.

J. B. Williamson is one of thousands of people who has recently received the message via e-mail.

"I got to work early one day and I opened my e-mail and that was sitting there, glaring at me," Williamson said.

What Williamson received is what authorities are calling the Nigerian scam.

The writer of the letter claims to have funds trapped in Nigeria and he needs help to get the money out.

"They say if you give them your account number, they'll deposit money in your account, and then you'll get millions in return."

Williamson didn't fall for the scam, but authorities said that millions of people all over the world have.

In fact, the scam has cost Americans $100 million in the last three years and is one of the biggest scams online, authorities said.

London's Metropolitan Police said that six people were arrested last month in South Africa involved in the scam.

Police said that the six were part of an international fraud and drug-dealing cartel.

Because the scam has become so prevalent, the U.S. government recently opened an office in Nigeria.

Meanwhile, the Nigerian government has set up a unit in London to help fight the scam.

For more information, log onto www.met.police.uk/fraudalert/419.htm.