The Baxter Building was one of the first targets Deadpool hit at the start of his killing spree against super-humans.

After killing The Thing, Deadpool seemingly used a machine which "melted" Richard's entire body, killing him. In his deathbed he told Sue that he left his children in the Negative Zone as the only way to save them, but they couldn't be brought back as the Portal was destroyed, either in the fight or by Reed himself, in order to prevent Deadpool from getting them.^[1]

Seemingly those of Reed Richards of Earth-616.