The U.S. has lost quite a few astronauts: three during training for the Apollo 1 mission, seven during liftoff of the shuttle Challenger, and seven on the shuttle Columbia during re-entry. But no Americans have actually died in space. However, three cosmonauts died in orbit during the Soyuz 11 mission in 1971, as they began their journey home from Russia's Salyut 1 Space Station.
Throughout Russia, the disaster brought about an unprecedented wave of mourning. People wept openly in the streets for three men who for over three weeks had appeared nightly on their television screens—cosmonauts who were being presented as human beings and not cold, faceless supermen—and who had offered a clear response to Apollo that the Soviet Union was back in the manned space business and firmly in the lead. Now, instead of three heroes, bearing broad smiles and bedecked in medals and garlands of flowers, all the Soviet people had was … three funerals.
Read what happened to the Soyuz 11 crew at Real Clear Science.