Only three people have actually died in outer space, as of 2014. During the 1971 flight of the Soyuz 11, three Soviet cosmonauts died when a ventilation valve ruptured, asphyxiating the crew and exposing them to the vacuum of space.
The disasters that destroyed the Challenger and the Columbia space shuttles both occurred inside the Earth's atmosphere. Challenger exploded 73 seconds after lift-off, while Columbia broke apart on re-entry. The 1967 fire that killed the three-man crew of Apollo 1 took place during a ground test of the command module.
The first in-flight fatality on a space mission occurred when the Soyuz 1 capsule crashed in 1967. The descent module, carrying cosmonaut Vladimir Komarov, crashed due to a parachute malfunction.