The suspect is identified as 33-year-old Curtis Smith of Coatesville, Pa.
Investigators say Smith entered the Justice Center around 11 a.m. with a knife, and attacked a sheriff's deputy, slashing him.
The district attorney said another deputy opened fire, shooting Smith.
Smith was rushed to Paoli Hospital but later died.
The deputy who was attacked is being treated for injuries to his arm and hand.
The deputy who opened fire is being interviewed.
District Attorney Tom Hogan revealed Smith's connection to the White House incident on March 1, 2015.
Court documents say Smith climbed over the top of a stone wall at the South East vehicle entrance. He then walked along the sidewalk, according to the documents, when he was approached by the Secret Service.
He was arrested for unlawful entry, but by the end of April had reached an agreement with authorities whereby he wouldn't be prosecuted if he stayed of trouble.
His next court date was scheduled for October 9th.
VIDEO: Witness describes shooting scene
David Widdowson tells Action News he was sitting outside the Justice Center when he heard three gunshots.
"I seen one guy get wheeled out on a stretcher, and a police officer also get wheeled out on a stretcher," he said.
Stay with Action News and 6abc.com as more information becomes available.