At least six people were killed and 31 injured when a rain-induced landslide hit a gold-mining village in a mountainous region of the southern Philippines, officials said Wednesday.

The landslide Tuesday night struck Masara in Davao de Oro province on Mindanao island, provincial disaster official Edward Macapili told AFP, destroying houses and engulfing two buses used to transport mine workers.

Rescuers were digging through mud to reach at least 20 people trapped inside the buses, Macapili said.

At least 28 people were on board the buses when the landslide hit, but eight managed to escape unhurt through the windows before the mud engulfed them, he said.

The buses had been outside a gold mine operated by the Philippine company Apex Mining in Masara village where buses drop off and pick up workers.

Aerial video showed a deep, brown gouge down the side of a forested mountain that reaches the village below where a number of houses had been destroyed.

Land above the landslide appears to have been cleared for crops.

Rescue teams from across the region have been deployed to help search the large area under mud, Macapili said.

"We have equipment but we're mostly doing it manually because digging with backhoes is dangerous as you don't know if there are people trapped beneath the debris," Macapili said.

Six bodies have been pulled out so far, an official from the Maco municipal disaster agency said, but it was not clear if they were on the buses.

Among the 31 villagers injured in the landslide, two were seriously hurt and were airlifted to a hospital in Davao city for treatment, Macapili said.

A total of 46 people were reported missing, he said. It was not immediately clear if that figure included the 20 trapped on the buses.

The landslide appears to have caught people by surprise.

"There was no sign that a landslide would occur because the rains stopped on Thursday and by Friday it was already sunny and hot," Macapili said.

Forced evacuations

Macapili said an earthquake shook the village shortly after the landslide. The search effort was halted at midnight because it was too hazardous to continue, but resumed at daylight, he said.

He said there was a mining tunnel beneath the mountain, but he did not know if it had been damaged by the landslide.

In a statement to the Philippine Stock Exchange, Apex Mining said it had reduced operations as it assists the rescue effort with equipment, personnel and food.

Meanwhile, hundreds of families from Masara and four nearby villages have been forced to evacuate from their homes and shelter in emergency centres.

Rain has pounded parts of Mindanao off and on for weeks, forcing tens of thousands into shelters.

At least 18 people died from landslides and flooding in the region last week, the national disaster agency said in its latest update.

Landslides are frequent hazards across much of the archipelago nation owing to the mountainous terrain, heavy rainfall and widespread deforestation.

The Philippines is regularly ravaged by storms, with scientists warning they are becoming more powerful as the world gets warmer because of climate change.