A United Parcel Service worker was seriously hurt today after he fell 25 feet while working on a grounded cargo plane at the Daniel K. Inouye International Airport.

American Medical Response paramedics responded to the fall at about 6:15 a.m. at 128 Mokuea Place, the air cargo facilities section of the airport.

Shayne Enright, spokeswoman for the Emergency Medical Services, reported the UPS employee was inside the grounded cargo plane when he fell onto the tarmac. He sustained head injuries and was treated and taken to a hospital in serious condition. It’s unclear what type of work the employee was doing when he fell.

Jim Mayer, spokesman of UPS Airlines based in Kentucky, said they will conduct an investigation into the accident. “Safety is a core value at UPS,” Mayer said.

Tim Sakahara, spokesman for the Department of Transportation, said airport operations were not affected.