A South Island mountain trek required emergency service intervention after the group ended up trapped.

One of the group members had a broken arm, according to those involved.

South Island police received reports yesterday of the group trapped on Mt Somers, near Mt Hutt as rising water levels and bad weather hampered their trip.

A helicopter was initially dispatched in an attempt to rescue them, however, the worsening weather meant the crew were unable to locate the group.

At midnight, three search and rescue teams were dispatched, according to police, and used a personal locator beacon activated by the group to find them.

The group was then taken to the Pinnacle Hut, 12km north of the mountain where extraction is set to take place today.