At least six people died and undetermined others went missing on Monday when five passenger motorcycles were buried by a landslide in a southern Philippine city, officials said.

The landslide was triggered by heavy rains in village of Valencia City, Bukidnon province during the night.

"It rained for about three hours, loosening the soil, and causing the landslide at the highway. Soil and boulders fell down. This is a mountainous area," said Benito Ramos, executive officer of the National Disaster Risk Reduction and Management Council ( NDRRMC).

Ramos, the concurrent administrator of the Office of Civil Defense, said the landslide buried the passing passenger motorcycles with extended seat. The modified motorcycles, which are the primary mode of transportation in the area, can carry up to five passengers each.

The landslide occurred around 7 a.m. in Lumbayao village, said Lt. Col. Jose Maria Cuerpo, commander of the Army's 8th Infantry Battalion, whose soldiers were among those who responded to the scene.

Cuerpo revealed that there were intermittent rains in the area for the past weeks. "It probably triggered the erosion, loosening the ground. It probably couldn't endure the rains for the past weeks," he said.

"Based on the report I got from my men, they've recovered six bodies. There are undetermined number of missing. We are still determining how many people are missing and at the same time identify them," said Cuerpo.

Maj. Eugenio Julio Osias, commander of the Army's 4th Civil Military Operations Battalion, said soldiers and other rescue personnel who responded to scene initially searched manually, digging using their bare hands, until equipment arrived.

Osias said 4th Infantry Division commander Maj. Gen. Victor Felix has ordered the deployment of all available troops to help in the search and rescue operations.

"Other victims were buried alive," said Osias, referring to the still missing victims. Osias could not say the number of the missing victims.