Philippine Volcano Mt. Mayon Erupts, Spewing Car-Sized Rocks: At Least 5 Dead [VIDEO]

Mayon volcano, one of the most active volcanoes in the Philippines, unexpectedly erupted Tuesday, reportedly spewing car-sized rocks towards nearly 30 surprised climbers, killing at least five and prompting the helicopter evacuation of more than a dozen others.

From a distance, a huge mushroom cloud of ash and gas was seen billowing from the mountain.

"Five killed and seven are injured, that is the latest report," National Disaster Risk Reduction and Management Council chief Eduardo del Rosario said, according to the BBC.

Falling rocks raining down from the ash blast caused death and injury.

"The injured are all foreigners ... They cannot walk," said Albay provincial Gov. Joey Salceda, according to the Washington Post. "If you can imagine, the boulders there are as big as cars. Some of them slid and rolled down. We will rappel the rescue team, and we will rappel them up again," he said from Legazpi, the provincial capital at the foothill of the mountain.

Among those killed were four German nationals and their Filipino guide. Mayon is a popular hiking destination and the eruption was apparently unexpected.

Twenty people were reportedly nearing the volcanoes summit when the explosion occurred.

"It was so sudden that many of us panicked," Jun Marana, a local resident, said to the AFP news agency. "When we stepped out we saw this huge column against the blue sky."

The eruption was reportedly a steam-driven eruption, what the BBC reported as a "normal process" in any volcano. Renato Solidum, the chief state seismologist, told BBC that there was no need to evacuate locals.

Famous for its near perfect cone, the 2,460-meter (8,070-foot) high stratovolcano in a national park of the same name about 200 miles southeast of the capital Manila. It has erupted at least 48 times since record keeping began, most violently in 1814 with an eruption that killed more than 1,200 and devastated several towns, the BBC reported. It last erupted in 2009, requiring the evacuation of tens of thousands.