UPDATES:  Typhoon Pablo killed at least eight people in the Philippines on Tuesday and there were fears the toll could rise sharply as the strongest storm to hit the country this year brought scenes of devastation.

Authorities were checking reports that a flash flood swept away an army truck with up to 30 soldiers and 20 civilians on board on the southern island of Mindanao, where the storm made landfall at dawn.

The typhoon brought driving rain and packed gusts of up to 210 kilometres (130 miles) an hour, toppling trees and power lines, causing localised flooding and forcing more than 50,000 to seek refuge in emergency shelters.

At least eight people were confirmed killed, including an elderly woman who was crushed to death when a tree fell on her house, a motorist who was pinned down by a coconut tree, and a soldier who drowned, rescue officials said.

The cause of death of the other five was not specified.

Civil defence office chief Benito Ramos said the report of the army truck swept away came from the southern town of New Bataan.

"There was a platoon of about 30 soldiers that deployed there in preparation for the typhoon," he said.

Four fishermen were also reported missing off Mindanao's east coast, said Freddie Bendulo, planning and development officer of Davao Oriental province.

A weaker Pablo headed for the Sulu Sea in the late afternoon, changing course westward after briefly threatening the central tourist islands of Bohol, Cebu and Negros, the state weather service said.

Hundreds of people are killed each year by the 20 or so tropical cyclones that hit the Philippines, but Ramos said the confirmed casualties so far from Pablo were down due to government efforts to move people to safety.

"So far, casualties have been minimal. We attribute this to the cooperation of our people and the efforts of local officials," he told reporters.

Winds blew roofs off some buildings and residents of coastal and low-lying communities in Mindanao moved into shelters as floods hit some areas, residents and AFP reporters said.

Television footage also showed logs being swept down Mindanao's Sumilao river, and utility workers cutting up fallen trees that were blocking highways.

More than 53,000 people had moved into nearly 1,000 government shelters by early Tuesday, the civil defence office said.

Television footage showed large numbers of people lying on mats or cardboard sheets on the concrete floors of gyms.

A total of 145 flights to and from Mindanao and the central islands had been grounded since Monday night and more than 3,000 ferry passengers were stranded as vessels were ordered to stay in port, the civil defence office said.

Large parts of Mindanao, which is not normally hit by typhoons, were without electricity after power was cut to reduce the risk of fires and electrocutions, said Liza Mazo, a regional civil defence official.

People living in the path of the storm did what they could to protect their homes and possessions.

"We have taken our pigs and chickens inside our house because their shed might be destroyed," 46-year-old shopkeeper Marianita Villamor from the southern farming town of San Fermin said.

In Cagayan de Oro city, where giant waves crashed down on the shoreline, mayor Vicente Emano said on ABS-CBN television that police rounded up all residents of low-lying areas and moved them to government shelters.

In Tagum city, hotel waiter Edgie Atilano, 23, said he and his family hunkered down in their home as Bopha bore down.

"At 3:00 am, we were woken by strong rain and howling winds. Trees and branches started snapping off near the house," said the father-of-two.

"This is my first time to experience a strong typhoon. It was a bit scary."