Violence against federal legislators is less common than assassination attempts against presidents, but the deliberative branch has seen its share of tragedies and near-tragedies.

The most recent shooting of a member of Congress took place only six years ago when the Arizona Democrat Gabby Giffords was shot in the head during a constituent event in Tucson in 2011. Giffords survived, but was forced to leave Congress because of her injuries. After wounding her, the gunman shot and killed six other people at the event, including federal judge John Roll. Giffords has since turned her attention to campaigning for stricter gun laws. On Twitter, she sent her regards to those injured Wednesday and praised members of the Capitol Police.

My heart is with my former colleagues, their families & staff, and the US Capitol Police- public servants and heroes today and every day. — Gabrielle Giffords (@GabbyGiffords) June 14, 2017

No member of Congress has been killed on U.S. soil since the assassination of New York Senator Robert Kennedy in 1968. He was the third legislator to die in the line of duty in the 20th century and the 14th overall in American history. Because Kennedy was running for president at the time, public attention focused on increasing security measures for presidential candidates. All major-party nominees have subsequently received Secret Service protection, as well as some high-profile contenders during the primaries. Illinois Senator Barack Obama began receiving round-the-clock protection in May 2007, far earlier than any other presidential candidate.

Two House representatives were also subsequently killed outside the country after Kennedy’s death. Followers of People’s Temple leader Jim Jones killed California’s Leo Ryan outside Jonestown in Guyana in 1978, where Ryan was investigating reports that the cult was holding some of his constituents against their will. In 1983, Soviet air forces shot down KAL Flight 007, a commercial airliner traveling from New York City to Seoul, over the Sea of Japan while Georgia’s Larry McDonald was traveling aboard.