Typhoon Mangkhut, which so far is the planet’s most intense storm this year, rammed into Hong Kong on Sunday, causing significant damage.

The storm, which had battered the northern Philippines with the strength of a Category 5 hurricane, weakened slightly while crossing the South China Sea but was still a force to be reckoned with in Hong Kong.

Mangkhut prompted the Hong Kong Observatory to issue an exceptionally rare Signal 10 on its 1-to-10 scale for storms. The agency warned residents to remain “indoors … to avoid flying debris.”

The right-hand eyewall — the worst part of the storm — made a direct hit over Hong Kong. Winds clocked in at 109 mph in the city. Storm surge up to 11 feet set record water levels in most spots; in Hong Kong proper, the ocean climbed to its highest level since at least 1904. Waves just offshore towered up to 45 feet.

Chinese state media reported that 200 phone lines were required to handle the number of calls coming in. The storm stranded tens of thousands of passengers at Hong Kong International Airport, where air travel was suspended Sunday — resulting in 889 delays or cancellations.

Most memorable perhaps were videos showing shards of glass whipping through city streets as razor-sharp projectiles. The high-rise buildings are designed to sway with the wind to reduce the buildup of tension. Some wobbled more than five feet at the top. But that doesn’t extend any protection to the windows. Once one shatters, the rest are much more prone to break, thanks to changing interior pressure forces with each incoming wind gust.

Effects on the Philippines

Before the storm hit Hong Kong, it battered the island of Luzon on Saturday, bringing winds that topped 150 mph and inflicted widespread destruction.

Mangkhut, known in the Philippines as Ompong, was responsible for the worst conditions in the province of Cagayan since it was struck by Typhoon Megi in 2010. Mangkhut has killed at least 81 people in the Philippines.

A Signal 3 alert was hoisted by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). It advised that “very heavy damage” to structures and severe impacts to “most residential and institutional buildings” could be expected. In upgrading the alert to a rare Signal 4, the agency eerily warned that “it may be too late” for evacuation.

The scale used to go up only to 4, but after Super Typhoon Haiyan in 2013, PAGASA decided to add a Signal 5. Since its implementation in 2015, it has not been used.

In addition to 150 mph winds, Mangkhut caused devastating mudslides in the mountainous western portions of Luzon. Forty gold miners perished operating an illegal mine when their bunkhouse was swept away Saturday evening. This was in the village of Itogon. About 10 miles northwest in the city of Baguio, 30.45 inches of rain was recorded.

As of Wednesday, there were no active tropical cyclones anywhere on Earth.