A volcano erupted on a small island in southern Japan on Friday, spewing black clouds of ash and rock towering into the sky and prompting authorities to tell residents to evacuate the island.

No injuries were reported after Mount Shindake erupted about 10 a.m. (9 p.m. ET Thursday) in spectacular fashion, sending dense pyroclastic flows of rock and hot gases seaward, the Japan Meteorological Agency reported.

The agency raised the volcano alert level for Kuchinoberu island, where Shindake is located, to five, the highest on its scale. Shindake also erupted in August last year for the first time since 1980.

A military helicopter was sent to survey the island and assess damage. Chief government spokesman Yoshihide Suga told reporters in Tokyo that the Coast Guard had dispatched a ship to help evacuate the residents.

Nobuaki Hayashi, a local village chief, said about 120 of the island's 137 residents were gathered at a local evacuation facility.

"There was a really loud, `dong' sound of an explosion, and then black smoke rose, darkening the sky," he told the national broadcaster NHK. "It smelled of sulfur."

Hayashi said a few people on the island were still unaccounted for, and some had yet to reach the shelter as they had to travel by boat.

"The skies here are blue, but smoke is still rising to the west," he said.

Kuchinoerabu island in the Ryukyu archipelago, 50 miles southwest of the main southern island of Kyushu, is a national park. Tourism and fishing are the main activities on the heavily forested, mountainous island.

Footage from NHK showed the mountain shrouded in light gray ash as the clouds from the eruption cleared.

Kuchinoerabu can be reached only by a once-a-day ferry from Yakushima island, about 7 miles to the east, which has an airport and a population of more than 13,000 people.

Japan, which sits atop the Pacific "Ring of Fire," has dozens of volcanoes and is frequently jolted by earthquakes.

Authorities recently closed part of a popular hot springs about 50 miles from Tokyo because of fears Mount Hakone, which sits to the southeast of Mount Fuji, might erupt.

The eruption last September of another volcano, Mount Ontake in central Japan, killed 57 people.