Spooked by the possibility of identity theft, increasing numbers of people are taking a radical approach to thwart criminals: They are putting their credit reports on permanent freeze.

A frozen credit report prevents almost anyone from using your name to take out a loan or sign up for credit, such as a credit card, a bank account or cell phone service. That is because, with a freeze in place, potential new creditors can't get access to your credit record kept on file by the three main credit-reporting bureaus without your explicit permission.

Michael Dana, a Dallas police detective, chose to freeze his credit reports after a Texas law took effect last month that made freezes available to all residents. Dana says he received several notices from financial institutions and the government saying that some of his personal information may have been compromised. "You can try to shred all your documents," says the 42-year-old. But "I'd rather shut my credit down and have the best security in place and not be a victim at all."

An estimated 50,000 to 70,000 people have so far signed up for credit freezes, according to the Consumer Data Industry Association, a trade group that includes the three credit bureaus. Consumer groups expect that number will grow after the bureaus — Experian Group Ltd., TransUnion LLC and Equifax Inc. — recently announced plans to offer credit freezes nationwide by next month. The bureaus' action comes after 39 states and the District of Columbia enacted laws in recent years allowing consumers to freeze their credit, though some states limit the option only to identity-theft victims.

Florida enacted a credit-freeze law last year, and Jimmy Glass and his wife signed up the same day. "Just the thought of someone else being able to assume your identity and rack up thousands of dollars in your name — that's just unthinkable," says Glass, of Orlando. "I have all the credit cards I need, no mortgage and no need for any car loans, so I just decided to shut it down."

Sometimes a brush with identity theft prompts people to take action. Dave Schreima of Long Beach, Calif., says someone recently got hold of his bank-account number and started making unauthorized withdrawals. "I had already decided to freeze my records. That just kind of prompted me that this is the time to do it," says the 49-year-old retired computer programmer.

"New account fraud is more serious than people hijacking your current accounts because you can go for a very long time and not realize that there's an account in your name at a store you never shop in," says Claudia Bourne-Farrell, a spokeswoman at the Federal Trade Commission.