The sonderkommandos mounted the uprising in a hurry. The krematorium IV Kommando rebelled after they knew they were about to be liquidated. They used only blunt weapons and self made grenades and set the krematorium 4 on fire (only one). The rebellion wasn't planned from the start.
The movie mentions the rebellion taking place in 'Number One' and 'Number Three' Crematorium in Birkenau. In reality these crematoria were numbered 2 and 4 (the number 1 crematorium was in the main camp Auschwitz 1). The unit working in Crematorium 2 was known as Kommando 1, however.