The typhoon made landfall at 1.40am local time (8.40am BST) on Saturday, September 15 in Baggao, Cagayan.
As torrential rain and severe winds lashed the northernmost part of the Philippines, news came of two victims of the storm.
Both of those killed were women, their deaths the result of rain-sodden hillside collapsing, according to news agency AFP.
You can find all the latest images from Typhoon Mangkhut here as the storm hits today.
Philippine state weather agency PAGASA have since downgraded the domestic threat level, but have warned the danger was far from over.
Continued storm surges and torrential rainfall could trigger floods and more landslides.
Three dams have been opened in the worst-hit area of Luzon, to release water following persistent heavy rainfall.
PAGASA meteorologist Rene Paciente said: ”We are asking the people to remain alert and continue taking precautions.”
Mangkhut, known locally as Ompong, has been described by the World Meteorological Organisation as the strongest tropical cyclone the world has faced so far this year.
Images from the Philippines show houses ripped apart by the 200mph winds, with debris littering the streets.
Residents have taken to beaches to forage for any recyclable materials that may have washed ashore, but in doing so face battling mountainous waves.
TYPHOON MANGKHUT PATH TRACKER LIVE: THOUSANDS EVACUATE — PHILIPPINES STRUCK BY 130MPH WINDS
Water has risen up to waist height and is running through the streets, with trees strewn across roads in some areas.
More than 105,000 people have been relocated to emergency shelters, as despite the storm moving fairly swiftly, storm surge warnings remain in place.
The storm conditions triggered by Mangkhut may remain until Monday.
The eye of Mangkhut is now over the South China Sea, as it continues on its path toward Hong Kong.
Updates from the Joint Typhoon Warning Center have measured wind speeds of 195mph with higher gusts.
Hong Kong is expected to start feeling strong winds and heavy rain today, growing in intensity as the storm draws ever closer.
Mangkhut is predicted to make landfall in Hong Kong on Sunday morning local time and then move to southern China on Sunday night.
In preparation for Mangkhut reaching China, flights have been cancelled and residents are being warned to prepare for severe weather conditions.
Mangkhut is expected to hit in the Chinese province of Guandong near the cities of Yangjiang and Zhanjiang.