WASHINGTON (AP) — The Internal Revenue Service official at the center of the storm over the agency's targeting of conservative groups told Congress on Wednesday that she had done nothing wrong in the episode, and then invoked her constitutional right to refuse to answer lawmakers' questions.

In one of the most electric moments since the IRS controversy erupted nearly two weeks ago, Lois Lerner defended herself during a brief appearance before the House Oversight and Government Reform Committee. The committee is investigating the agency's improper targeting of tea party and other conservative groups seeking tax-exempt status, and Lerner oversees the IRS office that processes applications for that status.

"I have done nothing wrong," said a stern-looking Lerner, sitting next to three other witnesses and reading from a written statement. "I have not broken any laws. I have not violated any IRS rules or regulations and I have not provided false information to this or any other committee."

Lerner then said she would invoke her Fifth Amendment right to avoid incriminating herself. Nine minutes after she began speaking, committee Chairman Darrell Issa, R-Calif., excused her and Lerner left the hearing room through a rear door, escorted by her lawyer and several other men.

The men quickly whisked Lerner into an elevator, where several of the men physically pushed back television camera operators who were trying to film them.

Lerner's refusal to answer questions was not a surprise. Her attorney, William W. Taylor III, wrote a letter to the committee this week saying she would do so.

Lerner revealed the agency's targeting two weeks ago and apologized for the actions.