Two people were freed overnight after being trapped in the Monongahela Incline, Pittsburgh public safety officials said.

The city’s EMS Rescue Division was called to the incline overnight Thursday into Friday to help two riders who were stuck when the cars stalled about 80 feet from the stations.

One person was trapped in each car from about 10:30 p.m. Thursday until they were rescued around 1 a.m. Friday., Pittsburgh Regional Transit spokesman Adam Brandolph said.

The incline remained closed Friday as officials worked to determine what caused the issues. It will remain closed “until further notice,” Brandolph said in a statement Friday.

Brandolph said officials are unsure why the incline stopped working.

While the incline is closed, shuttle buses will transport riders between the upper station and Station Square below.

In November, 27 people were trapped on the incline when both cars stopped shortly after leaving their stations. It took crews nearly four hours to rescue everyone from the stuck funicular.

The Monongahela Incline opened in May 1870 and is the oldest continuously operating railway system of its kind in the country. It transports more than half a million riders annually, according to Pittsburgh Regional Transit.