Record-breaking rainfall paralyzed much of Hong Kong on Friday, with flash flooding submerging metro stations and trapping drivers on roads, as authorities suspended schools and urged the public to seek safe shelter.

Photos and videos showed residents wading through murky brown floodwaters as heavy rain continued to inundate the densely populated city of 7.5 million. In some low-lying areas, streets were transformed into surging torrents, with authorities forced to rescue motorists stuck in their vehicles.

The deluge began late Thursday night, with the Hong Kong Observatory recording more than 158 millimeters (6.2 inches) in rain between 11 p.m. and midnight, the highest hourly rainfall since records began in 1884, the government said in a news release.