New Zealand's Mount Tongariro volcano sprang suddenly to life on November 21, spewing ash nearly 20,000 feet into the air, canceling regional flights and coating everything in its vicinity in a layer of fine gray silt.

The volcano had erupted in August after being dormant for more than a century, according to news accounts. But since then it had been quiet.

"The eruption itself gave us no warning whatsoever, it just snuck up on us," said an unnamed observer to BBC News in the video below, which showed pictures of people hosing down their front porches and leaving footprints as they walked.

One resident described it as a mushroom-looking cloud not unlike that of a nuclear bomb. No one was reported hurt, though numerous flights were canceled as the ash cut visibility. About 50 hikers in Tongariro National Park, including numerous schoolchildren on a class trip, had to scurry to safety during the five-minute eruption, reported the website Live Mint. The mountain is closed to hikers for at least three days.

The volcano on the North Island served as one of the backdrops in The Lord of the Rings trilogy, Live Mint reported, and the national park was the landscape used to depict Mordor.

Civil defense officials warned there could be more eruptions, New Zealand's Sky News television station reported.

"GNS Science indicates that there remains a significant probability of sudden eruption within the next week," Civil Defence said in a statement quoed by Sky News. "Future eruptions could also occur with little or no warning."

Below, some aerial footage of the eruption from Russian TV, then the BBC report to explain what happened on the ground. Under that is the eruption in real time.