SAN FRANCISCO -- Identity theft is one of the nation's fastest growing crimes, leaving people everywhere at risk. A KTVU investigation has uncovered a potentially serious security breach from San Francisco city agency that has put some people's most private personal data literally out on the street.

Potentially thousands of people's personal information was exposed after a San Francisco agency left confidential files in unsecured curbside garbage and recycling bins.

It's trash day in the city and the scavengers are out rifling through the garbage bins in a San Francisco alley. A KTVU cameraman caught two individuals with pick-up trucks stopping briefly before hauling away armloads of paper. No one challenges them as they steal from the unsecured blue bins.

A closer look shows some of what they left behind: confidential documents from the San Francisco Human Services Department.

Lance Williams has lived on this Mission Street alley for two years. He says he's learned not to leave any of his personal information in the trash because people are constantly rummaging through the bins.

"Someone grabbed their hand in there and pulled out someone's social security card and an i.d. I think that's probably all you need to go places. And just seeing that sent it home that I could not leave anything out," said Williams

Peering into one of the bins, Williams illustrated how easily someone would be able to commit identity theft. "Well, already I have a first and last name. And unfortunately I see someone's social security number. I don't think I need to see any more than that."

When KTVU stopped to talk to Cati Okorie, she had just applied for general assistance at the San Francisco Human Services office on Mission Street. The agency handles the case loads of 8,000 San Franciscans and presumably safeguards the personal information it requires from its clients.

KTVU took her behind the building to show her where some of that information -- maybe her own -- might end up.

"Oh my god! People's information. They're supposed to have a lock on it. It's supposed to be shredded," Okorie exclaimed. "Don't they have a paper shredder? I have a paper shredder at home myself!"

In some cases entire case files were discarded. Blown up copies of social security cards, driver's licenses, passports, bank statements and other sensitive personal information were all left in these unlocked bins.

"Who's the supervisor of this whole place? I want to know. Can you explain how these are in an alley in an unlocked box?" asked Okorie.

Trent Rohrer is the head of San Francisco Human Services. Rohrer showed KTVU how the personal information is supposed to be disposed of, placed in locked bins.

"We do have a whole set of policies and procedures to prevent this stuff from happening, and clearly there are flaws in that," said Rohrer

So are people simply not following procedures, or is there criminal activity going on inside the city department?

"We'll go from top to bottom to see if there's an internal identity theft ring going on or if there's something external going on. We'll get to the bottom of it," said Rohrer.

Joanne McNabb is the chief of the California Office of Privacy Protection. She says eight million Americans were victims of identity theft last year. And she says there are laws regulating how businesses and governments dispose of personal information.

"Protecting personal information is protecting people. If personal information falls into the wrong hands, bad things can happen to people," explained McNabb. "It sounds like this would be an alley that would lead identity thieves to the good stuff that they're looking for. It's like cash. When you have hundred dollar bills, you're not going to leave them unattended

KTVU doesn't know where these trucks went with the Department of Human Services papers and the reams of personal information from its clients. Human Services says it's reviewing its procedures and investigating how the papers ended up on the street.

Almost immediately after KTVU discovered the security breech, San Francisco officials imposed a number of reforms, including many more secure waste paper disposal sites, new training for employees, and a new policy of never placing any garbage cans out on the street at the Department of Human Services.

There's no word if anyone was held accountable for what happened.