At least six hikers have been killed and nine injured after a chunk of a glacier broke loose in the Italian Alps.

Local authorities fear more could be dead as around 15 people are missing in the Dolomite mountains in northeastern Italy.

Of the hospitalised survivors, two were in grave condition, authorities said.

The chunk of ice, from the Marmolada glacier, slammed into hikers on a popular trail.

Rescuers said blocks of ice were continuing to tumble down.

The detached section is known as a serac, or pinnacle of ice.

Other hikers might be able to get down by themselves using the peak’s cable car.

Some hikers were tied together by rope, according to local emergency services.