BARCELONA, Spain (AP) — Commuter rail service serving Barcelona and northeastern Spain has suffered major disruption because of the theft of copper cables from a train installation, Spanish rail authorities said Sunday.

Thousands of commuters were stranded at train stations in and around Barcelona after trains couldn't run on several commuter lines.

The disruption to local transport came while more than 5.7 million voters were eligible to participate in a regional election in Catalonia.

Spain’s state-owned railway authority ADIF said that the theft of electrical cabling from a station just north of Barcelona in the town of Montcada caused “several fires in the cables of the signaling system.”

It said that the incident around 4 a.m. local time (0200 GMT) caused a “serious” impact to the local train service and affected all the rail lines.

Catalonia’s commuter rail service suffers regular delays, some because of similar acts of theft.