WASHINGTON (AP) — Secret Service Director Julia Pierson is scheduled to answer lawmakers' questions about an embarrassing White House security breach.

Pierson will face critical questions Tuesday from the House Oversight and Government Reform Committee about how a Texas Army veteran armed with a knife managed to not only climb over a White House fence untouched, but make it deep into the inner sanctum of the presidential residence.

Utah Republican Rep. Jason Chaffetz said Monday night that whistleblowers told his committee that the intruder ran through the White House, into the East Room and near the doors to the Green Room before being apprehended Sept. 19.

Pierson will also have to explain why members of Congress apparently weren't told initially of the full extent of the breach.

(Story by: Alicia A. Caldwell and Josh Lederman, The Associated Press)