Officials say the flames erupted Thursday afternoon at the 75-year-old Hersheypark Arena in Derry Township.
The facility is owned by Hershey Entertainment & Resorts, founded when Milton S. Hershey separated his chocolate manufacturing from his other businesses.
Hershey spokesman Tim Shellenberger says workers were putting a new roof on the domed building, but it's unclear if that caused the fire. He says the roof isn't in danger of collapse.
Firefighters extinguished the blaze after about two hours. Some emergency workers were treated for heat exhaustion.
The arena opened in 1936. Chamberlain scored 100 points there for the Philadelphia Warriors against the New York Knicks on March 2, 1962.