Other presidents have consoled the nation in times of grief: Ronald Reagan after the Challenger disaster in 1986, Bill Clinton after the Oklahoma City bombing in 1995, and George W. Bush after 9/11. President Obama himself did so after the Tuscson shootings in 2011.
But Americans have not always expected their president to play this role. On August 1, 1966, a disturbed ex-Marine murdered his wife and mother, then mounted a tower at the University of Texas at Austin, where he went on a shooting rampage that slew 14 more. Although the killings happened in President Johnson's home state, he did go on live television to console the nation. Instead, his press secretary read a brief statement calling for stricter control of firearms. (LBJ later repeated it for broadcast.)
The following year, the space program endured its first deaths in the line of duty. During a routine ground test on January 27, 1967, an Apollo spacecraft suddenly caught fire, killing astronauts Gus Grissom, Edward White, and Roger Chaffee. The White House Press Office issued this statement: "Three valiant young men have given their lives in the Nation's service. We mourn this great loss. Our hearts go out to their families." That was it: the president did not make an address to the nation, though he did attend funeral services.