Torrential rain triggered severe flooding across northeastern Spain on Sunday, leaving residents trapped in vehicles and homes in parts of Catalonia -- just a day after similar downpours caused travel chaos on the island of Ibiza.

Videos shared by local media showed raging brown torrents sweeping through streets, submerging cars, and carrying debris downstream.

Spain's national weather agency, AEMET, issued its highest red alert for the province of Tarragona, warning that up to 180 millimetres of rain could fall within 12 hours in the Ebro river delta.

According to Catalan fire service spokesman Oriol Corbella, the deluge took many by surprise, leaving people stranded 'inside vehicles, in buildings, on ground floors'.

In Santa Bàrbara, Mayor Josep Lluís Gimeno told regional broadcaster 3Cat that the situation had become 'very tense' as conditions worsened overnight. Local streams and ravines, he said, 'are completely overflowing and have invaded the entire centre of the town, dragging everything there is, containers and cars'.

The nearby village of Godall also suffered major flooding. Its mayor, Alexis Albiol, described 'a moment of chaos', telling 3Cat: 'All the cars that were in the streets near the ravine were swept away and are distributed throughout the village. I don't believe anyone in the village has seen the amount of water that has fallen in such a short time.'

Emergency crews were seen rescuing motorists trapped on a flooded motorway near Amposta, according to footage published by local media.

Catalan emergency services said they had received a surge in calls after 5pm, logging 998 incidents. Civil protection authorities extended a mass phone alert covering roughly 100 km along and near the coast, urging people to avoid travel and stay clear of rivers and streams.

Catalonia's regional leader, Salvador Illa, said that all schools, sports and community activities would be cancelled on Monday in five of the hardest-hit areas. He advised residents to stay home and work remotely wherever possible.

The torrential rains followed a red alert in the neighbouring Valencia region, which escaped major damage despite having endured Spain's deadliest floods in decades last year. Even so, some towns that were devastated in that disaster pre-emptively cancelled classes and outdoor events scheduled for Monday as a precaution. Click here for all our reports related to the Valencia Floods.

On Saturday, the same weather system battered the holiday island of Ibiza - the second time in two weeks it has been hit by flooding - before moving northeast across the Mediterranean and into Catalonia. ALSO READ: Ibiza & Formentera escape with limited damage after floods from torrential rain.

Scientists say climate change is amplifying such extreme rainfall events, as a warmer atmosphere holds more moisture that evaporates from an increasingly hot Mediterranean Sea, heightening the risk and intensity of floods across the region.

More torrential rain and flooding causes havoc across southern Catalonia - Spain in English