– The Federal Emergency Management Agency shared the personal addresses and banking information of more than 2 million U.S. disaster survivors in what the agency acknowledged Friday was a "major privacy incident."

The data breach, discovered recently and the subject of a report by the Department of Homeland Security's Office of Inspector General, occurred when the agency shared sensitive, personally identifiable information of disaster survivors who used FEMA's Transitional Sheltering Assistance program, according to officials at FEMA.

In a statement, FEMA press secretary Lizzie Litzow said the breach happened because "FEMA provided more information than was necessary" while transferring disaster survivor information to a contractor.

"We believe this oversharing has impacted approximately 2.5 million disaster survivors," said a Department of Homeland Security official who asked for anonymity.

He said 1.8 million people had both their banking information and addresses revealed, and about 725,000 people had just their addresses shared.

The U.S. government mishandled personal information from victims of some of the country's worst disasters — including hurricanes Harvey, Irma and Maria in 2017 — in a major privacy mishap that threatens survivors with "identity theft and fraud," according to the watchdog report. That report, dated March 15, estimated that 2.3 million people had been affected, slightly less than the estimate from the DHS official on Friday.

The security mishap involved a program managed by FEMA that places people affected by disasters in temporary housing. The agency shared "unnecessary" amounts of data — including home addresses and birth dates and in some cases more sensitive information about their bank accounts — according to findings of the Office of the Inspector General.

It is unclear if the data breach had led to identify theft or other malicious actions.

The Inspector General's report told FEMA it needed to install controls to make sure such data would not continue to be shared with contractors and that the agency needed to assess how wide the breach was and to make sure that data in the contractor's system was destroyed.

In the OIG's report, FEMA said that once it became aware of the problem, the agency installed a data filter in December to prevent unnecessary survivors' personal data from leaving its system.