UPDATED: May 26, 2015 5:03 p.m.

WASHINGTON — The IRS says thieves used an online service provided by the agency to gain access to information from more than 100,000 taxpayers.

The information included tax returns and other tax information on file with the IRS.

In a statement Tuesday, the IRS said the thieves accessed a system called “Get Transcript.” In order to access the information, the thieves cleared a security screen that required knowledge about the taxpayer, including the Social Security number, date of birth, tax filing status and street address.

The IRS said thieves targeted the system from February to mid-May. The service has been temporarily shut down.

Tax returns can include a host of personal information that can help someone steal an identity, including Social Security numbers and birthdates of dependents and spouses.

“These third parties gained sufficient information from an outside source before trying to access the IRS site, which allowed them to clear a multi-step authentication process, including several personal verification questions that typically are only known by the taxpayer,” the IRS said in a statement.

The agency added the matter is under review by the Treasury Inspector General for Tax Administration as well as the IRS’ Criminal Investigation unit.

The IRS says it will provide free credit monitoring services for the 100,000 taxpayers whose accounts were accessed.

“In total, the IRS has identified 200,000 total attempts to access data and will be notifying all of these taxpayers about the incident. As always, the IRS takes the security of taxpayer data extremely seriously, and we are working aggressively to protect affected taxpayers and continue to strengthen our protocols.”

All 200,000 taxpayers whose accounts had attempted unauthorized accesses will be sent a letter.

The main IRS computer system that handles tax filing submission was not involved in the breach, the agency says.

This is a developing story.

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