Pittsburgh Regional Transit said Wednesday morning almost all of its rail service has been halted by a power line collapse overnight.

One train car is still operating between South Hills Junction and Allegheny Station, according to a social media post from PRT.

Two shuttle buses each are operating between Library and South Hills Junction, Washington and South Hills junctions and South Hills Village and South Hills Junction, according to PRT.

Riders can then take inbound buses to downtown, the post said.

The collapse required crews to shut off power to the majority of the rail system, meaning no trains are able to leave the rail yard, according to PRT. The single operational car was already out of the yard by the time of the collapse, PRT said.

It did not say where the power line came down or when it expects normal service to resume.

“With temperatures at or below zero, we strongly suggest avoiding the rail system until the issue is resolved,” the post said.

As for PRT’s regular buses, they are operating where road conditions allow, though significant detours remain on numerous routes, according to PRT. Riders can expect service delays of 10 to 20 minutes.