Updated from 2:52 p.m. EDT

SAN FRANCISCO - The personal information of about 800,000 people who applied for jobs at

Gap

(GPS) - Get Report

could potentially be compromised as a result of a stolen laptop from a third-party vendor.

The apparel chain said Friday it began alerting the applicants, who sought positions over the phone or via the Internet between July 2006 and June 2007 and whose social security numbers were contained on the laptop.

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Contrary to Gap's agreement with the vendor, the information on the laptop wasn't encrypted. Local law enforcement has been notified, and an investigation is underway.

Gap uses more than one vendor to manage its job applicant data so not all those who applied for jobs between July 2006 and June 2007 will be affected.

"Gap Inc. deeply regrets this incident occurred," said the company's chief executive, Glenn Murphy, in a statement. "We take our obligation to protect the data security of personal information very seriously. What happened here is against everything we stand for as a company. We're reviewing the facts and circumstances that led to this incident closely, and will take appropriate steps to help prevent something like this from happening again."

Gap is offering the applicants a year of free credit-monitoring services with fraud resolution assistance, as well as a 24-hour helpline.

The stolen laptop contained personal information for people who applied for store positions with the company's Old Navy, Banana Republic, Gap and Outlet stores from the U.S., Puerto Rico and Canada.

Shares of Gap were recently up 16 cents to $18.46.