Japan's Mount Ontake volcanic eruption traps hikers

Several climbers have been injured in Japan after Mount Ontake volcano erupted, sending huge plumes of ash and stones into the sky.

Witnesses heard a 'thunder-like' boom before the eruption at the 3,067m (10,120ft) peak, situated between Nagano and Gifu prefectures.

Prime Minister Shinzo Abe says the army will help rescue some 150 climbers sheltering in lodges near the summit.

Officials have 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.

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

'There are 15cm (six inches) of ash on the ground,' she said.

Some climbers have managed to descend.

'I escaped with my bare life,' one told NHK.

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

Two of those injured have fractured bones caused by flying rocks, NHK said.

Three people are missing, believed buried under volcanic ash, it said. A fourth was rescued but remains unconscious, the broadcaster added, citing police.

Kiso Prefectural Hospital, near the mountain, said it had dispatched a medical emergency team.

'We expect a lot of injured people so we are now getting ready for their arrival,' said an official at the hospital.