Jakub Gutenbaum still squirms at the thought of scalding-hot walls in the basement where he hid while houses burned overhead during the Warsaw ghetto uprising.

Talking to The Associated Press on Thursday, the 83-year-old Gutenbaum recalled people in the basement lying on the floor with no clothes on in that "infernal heat," but then collecting the strength to stuff ventilation and cracks in the walls to prevent smoke getting into the basement.

Gutenbaum, his mother and little brother hid in the basement for 12 days, surviving the horror of the uprising — an against-all-odds revolt by hundreds of lightly armed Jewish fighters against a much larger Nazi force that broke out 70 years ago on Friday.

He will be among the ever-shrinking group of survivors from the ghetto who will attend a commemoration that will be led by Polish President Bronislaw Komorowski in Warsaw.

Europe's first open revolt against the occupying Nazi Germans, the uprising broke out when the Nazis decided to liquidate the ghetto and started to send its last remaining residents to death camps.

The fighters "knew that they had to die, but they wanted to leave a trace of their existence, hence those acts of heroism, a testimony to honor," Gutenbaum said.

He recalled how German troops came into the basement, forced everyone out at gunpoint and took them to Umschlagplatz, the departure point for trains taking ghetto residents to the gas chambers of Majdanek and other camps.

"You cannot even begin to describe what was going on at Umschlagplatz," Gutenbaum said. "Those SS men were bullying everybody, beating them, smashing skulls, demanding jewelry, demanding watches."

Gutenbaum's mother and brother were killed in the gas chambers of the Majdanek camp, but he survived with the help of other inmates, was moved to other camps and liberated by the Soviet Red Army.