At least one person has been killed and three others injured after a huge chunk of ice collapsed on a group of tourists visiting the Vilyuchinsky waterfall in Russia.

According to the Russian Emergency Situations Ministry, rescuers dug through a frozen mound at the base of the 130-foot-tall waterfall on the Kamchatka Peninsula in far eastern Russia to free at least four people trapped by the ice on Thursday.

All were pulled from the ice, and a boy and his father were flown to hospital.

The regional government said the boy was in intensive care with serious injuries.

“The father is in hospital with the child,” Marina Volkova, the Kamchatka Territory’s deputy minister of health, said. “The day before, they flew in from Vladivostok.”

Separate groups of tourists left the scene safely and no further casualties were reported, Russia’s Emergencies Ministry told the Tass news agency.

The ministry said it had dispatched a helicopter with rescuers, medics and investigators to the site and the collapse of the ice is under investigation.

The Vilyuchinsky waterfall – also known as the Tsar Icicle – is formed by water melting off of a glacier on the slopes of the Vilyuchinsky volcano and often freezes in the winter, according to the Siberian Times.

Cascading about 40m, the waterfall is one of the most popular tourist sites on the area and attracts many visitors yearly.