Metro Line 8 broke down on Thursday morning for some 90 minutes, leaving passengers stranded in stations during morning rush hour.

At 6:14am, the official Weibo account of Shanghai Metro warned all passengers that due to equipment failure, all trains on Line 8 operating between Quyang Road and Lujiabang Road stations would run at delayed intervals.

“The departure interval of trains will be longer,” Shanghai Metro announced on Weibo. “All trains are expected to be delayed for more than 15 minutes.”

At 7:07am, Shanghai Metro said the delay was estimated to be over 20 minutes as it was rush hour and emergency personnel were still dealing with an equipment failure.

The Metro operator temporarily stopped passengers from entering stations on Line 8, as many were already overwhelmed by stranded passengers.

Many passengers wrote on Weibo that they were trapped inside Metro trains for quite a while; in some cases up to an hour.

The equipment failure was announced to have been fixed at 7:44am, but since many commuters were still stranded, Shanghai Metro said that passenger limiting measures at some stations would continue for another 30 minutes.

At 8:59am, Shanghai Metro said all operation of Line 8 had been restored. Passengers who were late to work or school because of the breakdown can go to Metro station information desks to get an apology note as documentary evidence of the breakdown.

The nature of the equipment failure was not revealed.