The Pittsburgh Post-Gazette and the Pittsburgh Tribune-Review report the two-story building collapsed around midday Monday in the city's Spring Garden neighborhood.
The worker and another man had been knocking bricks from a wall when the building collapsed.
The injured man, whose name was not released, was pinned under some of the rubble for a short period of time.
Officials say the man's injuries were serious, but did not appear life threatening.
A crew was later sent to the scene to tear down parts of the building that may have been left unstable after the collapse.
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