HONG KONG — The firefighters rushed to the disused mine outside Malaysia’s capital in a steady rain Wednesday evening, searching for a teenager who had slipped into a pond. The rescue effort quickly turned into one of the worst disasters the country’s emergency services have ever experienced, with six firefighters drowning in the dark, rushing waters, officials said Thursday.

The deaths come three months after rescuers in neighboring Thailand safely evacuated 12 boys and the coach of their soccer team from a cave, where they had been trapped for days. One diver died in that effort, which attracted global attention.

But in Malaysia, what began as a routine rescue went horribly awry with a shocking swiftness. Videos published online show the men struggling in choppy water, illuminated only by flashlights, with the sounds of shouts and rushing water filling the air.

Mohammad Hamdan Wahid, director general of the Fire and Rescue Department of Malaysia, told reporters attending the funeral of the men on Thursday that it was the most department personnel ever killed during a single rescue operation, the Malay Mail newspaper reported.