Authorities say the police chief and a rookie were on patrol when they spotted an open gate at the Sand Castle Winery on River Road.
Upon closer inspection, police say the two men also spotted an open door.
Chief James Sabath approached and, when he walked through the door, he fell 30 feet through the darkness down a freight elevator shaft onto the concrete floor of the winery's cellar.
Rookie officer Mark Compas, an Iraq veteran and son of a retired cop, heard his chief's screams and ran for the door. He too fell down the shaft.
"He said he remembers being in midair and next thing he knew he saw stars and he was spitting out teeth and blood and found his chief laying on the floor in the pitch dark," said Ed Compas, the officers' father.
Compas radioed for help. Both officers suffered multiple fractures and were airlifted to St. Luke's in Bethlehem where they underwent surgery.
"We're very saddened about it. Our hearts go out to the officers and their families. We hope they're going to be all right," said Hendrik Maxian of the Sand Castle Winery.
Compas was released Friday afternoon to have his broken jaw wired shut at another facility.
Chief Sabath remains in intensive care.
"I know his officers are worried about him, we're all worried about him and just hope that he has a swift recovery and comes back to work as soon as he can," said Sgt. Ed Murphy of the Pennsylvania State Police.
While investigators look into what happened, area police departments and the State Police are planning to help patrol Tinicum, which has just 5 officers.
"We're going to do the best we can so that the residents of Tinicum Township are covered for their emergencies," said Chief Duane Hasenauer of the Plumstead Twp. Police.
While the officers recover, the investigation into the accident is continuing.
Click here to get the latest Philadelphia news and headlines from across the Delaware and Lehigh valleys.