mainly Jews.
the vast majority were Jews, a large proportion were from the Warsaw ghetto.
310,000+ Jews were sent to Treblinka. The time period was between less than 3 months.
An estimated 850,000+ were Holocaust victims at Treblinka. It had the highest death toll after Auschwitz.
The most common way people died in Treblinka was by Gassing but not by Zyklon B but instead by Carbon Monoxide.
Lots of people died ----------- The inhabitants of the ghetto knew that they were going to be killed, whatever they did and that the ghetto was getting smaller and smaller as endless trainloads of Jews were sent to Treblinka.
Treblinka (I) began as a concentration camp for Poles.
Treblinka II was an extermination camp and only about 40 people survived - that is, were still alive at the end of World War 2 in Europe. None of them is particularly famous.
http://www.holocaustresearchproject.org/ar/treblinka/trebmap3.jpg
Treblinka was an extermination camp, not an ordinary concentration camp. The idea was to kill new arrivals as soon as possible. It served no other purpose. A very small number of new arrivals were made to help with the extermination process itself. In particular they had to dig mass graves and sort the belongings that the newly arrived and gassed victims had brought with them.
A widely accepted figure is about 870,000.
shooting them and gas chambers
The sole purpose of Treblinka was to kill Jews and gypsies as quickly as possible after their arrival. It was an extermination camp. A relatively small number of new arrivals were 'selected' for grave digging and sorting the possessions of gassed victims. For these reasons the camp was small, and the number of prisoners there was small, too - probably not more than about 1,500 at any time.