About 300 villagers were evacuated from the slopes of the Tungurahua volcano following a surprise eruption of ash, lava and incandescent rocks, a local mayor said Thursday.

"We were able to take them out last night from the most dangerous zones located on the flanks where the explosions occurred Aug. 16," said Juan Salazar, mayor of Penipe, 12 miles from the volcano.

No injuries were immediately reported.

Experts have warned that renewed explosions could come any time from the 16,575-foot-high volcano 85 miles south of the capital of Quito.

CountryWatch: Ecuador

A violent eruption in mid-August killed four people and left two others missing and still unaccounted for. Nearly 5,000 homes were destroyed or severely damaged and some 475,000 acres of farmland were covered by ash, the government has said. Thousands of people were also evacuated in July during an earlier eruption.

Salazar said unlike that eruption, which followed months of loud, booming explosions and rumbling, the smaller explosion late Wednesday came with no warning.

"There wasn't a single sound," he told Radio Universal. "There was fire and lava that made us take precautionary measures."

The upper slopes of the volcano have been mostly deserted since August. But Salazar said about 80 families had returned to attempt to plant vegetables in the ash-encrusted ground.

"They saw incandescent rocks coming down on the slopes and so they evacuated," he said.

Hugo Yepes, director of Ecuador's Geophysics Institute, said pressure has been building inside the volcano since early September.

"What we have seen now is evidence that something there could be something similar to the episodes in July and August" coming, he told Channel 4 television. "Inside the ground there is a chamber of magma much larger than the volcano itself."