Massive train disruptions in Germany left hundreds of passengers stranded on Saturday, as authorities worked to restore traffic following a technical malfunction. Some traffic has since resumed.

Train services in central Germany have been “massively affected” due to a technical fault, the German rail company Deutsche Bahn said.

There were widespread train cancellations in the greater Frankfurt area due to a radio communications failure, public broadcaster ARD’s news service Tagesschau reported.

Trains traveling to or departing from Frankfurt were affected, and traffic through the major travel and financial hub was halted, according to Tagesschau.

Hundreds of passengers were stranded at Frankfurt’s Central Station on Saturday, without knowing when they could resume their journeys, Tagesschau reported.

One of the biggest transport associations in Germany, the Rhine/Main Regional Transport Association, or RMV, said in a post on social media on Saturday that due to a technical fault in radio communications, “train services in the RMV area have been suspended until further notice” and that neither S-Bahn trains nor regional trains could run.

“The duration of the disruption cannot currently be foreseen,” RMV said at the time.

It remains unclear what caused the technical fault.

Later on Saturday, Deutsche Bahn said the technical problem had been resolved. “Rail traffic in central Germany is starting up again. There may be disruptions until the end of the day,” it said.

Frankfurt is one of the most important European transport hubs with around 1,200 local and long-distance trains in regular service every day, according to Tagesschau.