In November 1950 two Puerto Rican pro-independence nationalists attempted to assassinate U.S. President Harry Truman.

Both men were stopped before gaining entry to the house. One assassin and one police officer were killed by gunfire. Secret Service agents wounded the other assassin.

President Truman was upstairs in Blair house (during the renovation of the White House) and not harmed. 

This was the second attempted assassination of President Truman. The first attempt occurred in 1947 when President Truman was sent a letter bomb containing powdered gelignite that police exploded experimentally. The Palestinian terrorist Lehi militant organization (AKA the Stern gang) later claimed responsibility.