Emergency services said on Sunday that six people were killed and two injured after a passenger bus veered off a bridge and fell into a flooding river in northwestern Spain.

Survivors — the 63-year-old driver and a passenger — were pulled from the river by firefighters using a rope and were taken to nearby hospitals with varying degrees of injuries.

A police spokesman also told Reuters that the driver’s test results were negative for alcohol and drugs. The spokesman added that the search and rescue operation around the bridge has now ended, while engineers tried to find a way to safely recover the debris from the Lérez river.

The strong river current and its high flow due to heavy rains that swept the Galicia region hampered the efforts to recover bodies throughout the weekend.

The bus, belonging to the Monbus company, was traveling between the cities of Lugo and Vigo on Saturday evening and stopped at a repair center near the accident site, where it slipped off a straight path on the bridge for reasons still unclear and fell into the water in a drop of no less than 40 meters (131 feet) at around 9:30 p.m. local time (5:30 p.m. Eastern US time).

Emergency services were first alerted by a call from a passerby who noticed that the bridge's safety barrier was severely damaged. Shortly after, they received a second call from inside the bus as it was filling with water.

While the river remained above the flood threshold throughout the night, forcing emergency rescue workers to suspend the operation for nearly two hours before resuming it in the morning.

Authorities initially reported that a total of nine people were on the bus when it fell, based on the driver's testimony, although it is now believed that the number was eight based on missing persons reports submitted by relatives.

The head of the Galicia region, Alfonso Rueda, pointed to "very bad" weather conditions as one of the possible causes of the accident.