Media playback is unsupported on your device Media caption Mount Ontake erupted covering the area in a thick layer of ash

At least 30 people have been seriously injured in Japan after Mount Ontake volcano erupted, sending huge plumes of ash and stones into the sky.

More than 10 remain unconscious, police said. Some were covered by the debris.

The eruption at the 3,067m (10,120ft) peak, situated between Nagano and Gifu prefectures, trapped hundreds of climbers who were forced to seek shelter in lodges near the summit.

Some 230 have managed to descend - some 40 have yet to be rescued.

Prime Minister Shinzo Abe authorised army units to help those trapped.

Officials warned residents within a 4km radius of the risk of debris.

Mount Ontake last erupted in 2007.

"It was like thunder," a woman who runs a lodge near the summit told Japanese broadcaster NHK.

Image copyright Reuters Image caption Residents over a large area have been warned of the risk of falling stones

Image copyright Reuters Image caption Hikers were taken by surprise in an area that is a popular tourist destination particularly as autumn trees change colour

"I heard boom, boom, then everything went dark."

"There are 15cm [six inches] of ash on the ground," she said.

One of the climbers who managed to descend told NHK, "I escaped with my bare life."

"Immediately after I watched the eruption, I rushed away but I was soon covered with ash."