The death toll from the Philippines’ biggest storm this year has risen to 18, with the disaster service warning on Saturday of “serious devastation” in the hardest-hit areas.

Typhoon Rai wreaked havoc on the country’s southern and central regions, knocking out communications and toppling concrete power poles. More than 300,000 people were forced to flee their homes and beachside resorts.

Also read: In pics | Devastation caused by powerful typhoon that battered the Philippines

When Rai slammed into the renowned tourist island of Siargao on Thursday, it was a super typhoon with maximum sustained winds of 195 kilometres per hour (120 miles per hour).

As the hurricane barreled over the archipelago, its wind speeds slowed to 150 kph, ripping roofs off houses, uprooting trees, and showering streets with debris.

According to Mark Timbal, spokesman for the national disaster agency, more than 18,000 military, police, coast guard and fire personnel will join search and rescue efforts in the worst-affected areas.

“There has been major damage” in Surigao and Siargao, according to Timbal, referring to the typhoon’s worst-hit areas.

In Siargao and Surigao, the adjacent cities on the northern tip of Mindanao’s southern island, communications were still down.

The Philippine Coast Guard has posted photographs on social media showing widespread devastation in Surigao, including torn-off roofs, smashed wooden houses and palms stripped of their fronds.

Swaths of rice fields were submerged in aerial footage.

Nilo Demerey, Vice-Governor of Dinagat, told ABS-CBN that the typhoon wreaked havoc on the island near Siargao, killing at least six people.

The total death toll now stands at 18, with seven people still missing and two injured, according to the disaster service.

Also read: Powerful typhoon threatens Philippines, thousands evacuated

“Odette was extremely strong,” Demerey added, referring to the typhoon by its local name.

Residents “are trying to repair their houses because even our evacuation centres were torn down. They can’t seek refuge anywhere else… everything was destroyed.”

Rai emerged over the South China Sea on Saturday after hammering Palawan Island and was heading towards Vietnam, according to the state weather forecaster.

Rai made landfall in the Philippines late in the typhoon season between July and October.

Scientists have long warned that as the world warms as a result of human-caused climate change, typhoons will become more powerful.

The Philippines, which is one of the world’s most vulnerable countries to climate change, is slammed by an average of 20 storms and typhoons each year, destroying crops, homes and infrastructure in already destitute areas.