A mechanic died Monday after being sucked into a jet engine while passengers were boarding the plane, officials said.

National Transportation Safety Board spokeswoman Lauren Peduzzi said she did not know if any passengers saw the accident, which involved a Boeing 737-500 operated by Continental Airlines.

Peduzzi said there had been an earlier problem with the engine, so its metal covering was open at the time.

A total of 114 passengers and five crew members were boarding at the time, authorities said.

The NTSB was investigating.