Sobibor was a Nazi German extermination camp located on the outskirts of the town of Sobibór, Lublin Voivodeship of occupied Poland as part of Operation Reinhard; the official German name was SS-Sonderkommando Sobibor.
Jews from Poland, France, Germany, the Netherlands, and Czechoslovakia, as well as Soviet prisoners of war (POWs) (many of them Jewish), were transported to Sobibor by rail, and suffocated in gas chambers that were fed with the exhaust of a petrol engine.
One source states that up to 200,000 people were killed at Sobibor. Thomas Blatt claims that "In the Hagen court proceedings against former Sobibor Nazis, Professor Wolfgang Scheffler, who served as an expert, estimated the total figure of murdered Jews at a minimum of 250,000."
In the month of May 1942 the largest number of Jews were gassed, more than thirty-six thousand were brought to Sobibor from nineteen communities between the Vistula and the Bug.
After a successful revolt on October 14, 1943 about half of the 600 prisoners in Sobibor escaped; although most were later re-captured and killed, the camp was closed, bulldozed, and planted-over with pine trees to conceal its location days afterwards. A memorial and museum are at the site today.
An article about Operation Reinhard in swedish Wikipedia. The construction of Sobibor, Treblinka and Belzec exterminations camps with further links to other languages.