Around 10 killer whales were reported trapped in drift ice off the coast of Japan's northernmost main island of Hokkaido on Tuesday, local officials said.

The pod of killer whales, including calves, was seen from a small gap in the water's surface around 1 kilometer from the coast, according to the town of Rausu. An official said vessels cannot get close enough to the animals for rescue operations.

The town is located on the Shiretoko Peninsula in eastern Hokkaido. Shiretoko is recognized as a World Natural Heritage Site by the United Nations Educational, Scientific and Cultural Organization.

Photo shows a pod of killer whales trapped in drift ice in waters off Rausu, Hokkaido, on Feb. 6, 2024. (Copyright Wildlife Pro LLC) (Kyodo)

"Temperatures are currently low, meaning it is possible the killer whales became trapped between sheets of drift ice," an official at the Kushiro Local Meteorological Office said.

The incident comes after the 1st Regional Coast Guard Headquarters on Monday recorded the year's first day in which drift ice could be visually confirmed. By Tuesday, it had largely covered nearby waters.

With low temperatures continuing into Wednesday, the area of the drift ice is likely to expand.

"Killer whales are highly social animals. If they stay (in the area) as a group to protect their young, they can end up slowly dying from exhaustion," said Mari Kobayashi, professor of marine mammalogy at Tokyo University of Agriculture.

In a similar case in Rausu in February 2005, a number of killer whales died after around 10 of the animals became trapped in drift ice.