LISBON – The initial investigation into the fatal derailment of a well-known streetcar in Portugal revealed that a key cable linking the two carriages essentially broke.

Wednesday’s crash left 16 dead and injured 21 others. Officials called it one of Lisbon’s worst tragedies in recent memory.

The Saturday report by the Office for Air and Rail Accident Investigations detailed that the two carriages had only progressed about 6 meters (20 feet) when they abruptly lost the stabilizing force due to the severed cable.

The yellow-and-white streetcar is known as Elevador da Gloria and goes up and down a steep downtown hill. The cabin at the top sped downward.

“The cabin’s brakeman promptly engaged both the pneumatic and hand brakes in an attempt to stop the vehicle,” the report noted. “Unfortunately, these actions did not slow or stop the cabin, which continued picking up speed downhill.”

Upon examining the crash site, it became “evident that the connecting cable had failed” where it joined the carriage at the top of the hill, according to the report.

Known as a funicular, this type of streetcar operates on steel cables, using the weight of the descending car to help lift the other. It accommodates over 40 passengers, both sitting and standing.

The exact number of passengers in each vehicle at the time has not yet been determined, the report said.

The streetcar that crashed had been in use since 1914.

A comprehensive report with detailed findings and conclusions on the accident’s causes is anticipated in the future. Should a complete report not be feasible within a year, an interim report will be issued instead.