Hong Kong’s heaviest rainstorm since records began in 1884 flooded the financial hub’s streets and sent torrents of water rushing through subway stations, bringing much of the city to a standstill and forcing the stock market to halt morning trading on Friday.

The downpour, which caught many residents off guard and came just a week after a super typhoon shut the city, caused the observatory to raise its highest rainstorm alert and was expected to last until at least noon. Schools were suspended and workers stayed home as bus operators halted services.

There was 158.1 mm (6 inches) of rain recorded at the observatory headquarters in Tsim Sha Tsui between 11 pm Thursday and midnight, which was the highest on record since records began in 1884, the observatory said. More than 600 mm of rain was recorded over much of Hong Kong island in the past 24 hours, according to the observatory.

The observatory raised the highest “black” rainstorm warning at 11:05 p.m. local time Thursday. The stock market will suspend all-day trading if the warning remains in place at noon, according to a statement by the local exchange operator.

A black rainstorm warning means more than 70 mm of rain has fallen in an hour and is likely to continue. The topography of Hong Kong island — roads and buildings built into steep hillsides — makes the city vulnerable to flooding and landslides from torrential rain that typically comes during the summer months.

MTR Corp. said it suspended part of its Kwun Tong Line due to flooding near Wong Tai Sin station. KMB and Citybus both said they halted their bus services, with Citybus saying it will assess weather and road conditions before resuming operations.

The rain was caused by the remnants of Typhoon Haikui. A landslide warning is also in place.

The city’s leader John Lee told government departments to respond with all-out efforts to deal with the “severe” flooding in most parts of finance hub.

The city was shut down on Friday and Saturday last week due to Super Typhoon Saola. That storm, the strongest to hit the city since Mangkhut in 2018, toppled trees and blocked roads. It was only the sixth time in the past four decades that the observatory raised its highest storm warning.

The storms are the latest examples of extreme weather experienced around the world this summer. In late July and August, dozens of people died in northern areas of China including Beijing due to flooding from a typhoon.