The accident happened at West and North Moore Streets around 3:20 p.m.
Two people were taken to the burn center at Cornell Medical Center with non-life threatening injuries.
Authorities said the two are brothers who were working on the truck at the time of the accident. They suffered burns on various part of their body, officials said.
Firefighters worked quickly to secure the other propane tanks on the truck so they did not explode as well.
