U.S. Secret Service Director Julia Pierson said on Tuesday the recent White House breach by a man carrying a knife was unacceptable and promised it would not happen again.

"I take full responsibility," Pierson said in prepared testimony to a U.S. House of Representatives committee investigating the Sept. 19 intrusion. "What happened is unacceptable and it will never happen again."

Pierson told the House Oversight and Government Reform Committee that she ordered extra security measures around the White House immediately after the breach. She also said Homeland Security Secretary Jeh Johnson had requested an investigation."It is clear that our security plan was not executed properly," Pierson said.

She did not provide details of the breach in her prepared testimony, deferring some issues to a closed session with committee members to follow.

But Pierson did acknowledge the problems and missteps that have dogged the Secret Service in recent years. Those included a lone gunman firing shots at the White House in 2011, a prostitution scandal involving agents in Colombia in 2012 and a night of drinking in March that led to three agents being sent home from a presidential trip to Amsterdam.