Germany ? A German electric company said Sunday a high-voltage transmission line it shut down over a river to let a ship pass could have caused the chain-reaction power outages that left about 10 million people in the dark across Europe.

The blackouts Saturday night briefly halted trains in Germany and trapped dozens of people in elevators in France and Italy. Austria, Belgium and Spain also were affected, though supplies to most regions were restored quickly. No injuries were reported.

The outages raised fresh questions about the reliability of Europe’s interconnected power grids and drew an immediate call for stronger coordination.

French power distributor RTE said the problems in Germany caused a “brutal imbalance” in supply and demand of electricity across the continent.

“Such imbalances must be corrected immediately to avoid a complete meltdown of the European electric system,” the company said in a statement.