Mangkhut is already the storm of 2018, and is now packing sustained winds of 165 kilometers per hour (103 miles per hour), with gusts up to 205 kilometers per hour (127 miles per hour).
National police said 64 people had died there as of Sunday, mostly due to landslides and collapsed houses, with two additional deaths reported in China.
In Hong Kong, authorities also issued their maximum alert, with residents warned to stay indoors to avoid flying debris.
Philippine authorities said a baby and a toddler were among the 29 dead, a lot of them in landslides in mountainous areas that left at least 13 missing.
There is also concern over the economic cost of the typhoon, which has caused extensive damage to farmland in Cagayan, a key agricultural province.More news: Hazard 'maybe' the best in Europe, says Chelsea boss Sarri
A Philippine mayor says it's highly unlikely any of the 40 to 50 people who are feared buried in a huge mudslide set off by Typhoon Mangkhut can be found alive.
While the storm has weakened considerably since, it still caused massive amounts of damage as it swept into China on Sunday and is anticipated to continue into Vietnam in the coming days.
Typhoon Mangkhut continued its deadly march across southern China Monday, steadily losing strength after a cutting a disastrous path across the northern Philippines.
Authorities throughout those regions had been urged to dismantle structures vulnerable to heavy winds, strengthen port facilities and suspend large outdoor gatherings, the meteorological administration said. About 291,000 were forced to flee their homes as the storm tore across the island of Luzon, an agricultural area in the archipelago's far north, with winds gusting up to 158 miles per hour, equivalent to a Category 5 hurricane.
The rescue work halted for the night before resuming Monday morning.
It's expected to pass about 100 kilometers (62 miles) south of the Pearl River Delta - an area in southern China that includes the cities of Hong Kong, Guangzhou, Shenzhen, Zhuhai and Macau - at about noon Hong Kong time Sunday, according to the the HKO.
The workers used pikes and shovels to dig into the mud Monday morning, with the use of heavy equipment limited on the soaked ground.