Three leads suddenly opened in ice fastened to the shore off the coast of Barrow over the weekend, stranding 18 hunters on giant ice sheets floating out to sea.

Witnesses on shore and some hunters noticed the large cracks in the ice around 2:30 p.m. Sunday. They radioed the Barrow Volunteer Search and Rescue, and the group's coordinator, Arnold Brower Jr., quickly put word out on the local public radio channel.

He soon had a list of 23 people known to be out seal hunting or cutting trails across the ice to prepare for whaling.

The leads opened up fast, catching most everyone off guard, said Randy Crosby, director of the North Slope Borough Search and Rescue. The closest lead was about half a mile from shore and the farthest about three miles out. The hunters and whalers were scattered over about five miles.

"One of the groups was separated by two different leads," Crosby said.

Within an hour or so, the borough's rescue crews had plucked 16 hunters from the ice with its two Bell 214 helicopters. Two other hunters found their own way home across a lead before it widened, Brower said. The remaining people on the list were not in danger, he added. No one was harmed.

After everyone had been rescued, the helicopter crews returned to the floating ice to gather hunting gear, collecting 13 snowmachines, several sleds and two small skiffs used to retrieve harvested seals. The helicopters each made five trips over roughly three hours to rescue the hunters and their equipment.

Though rare, this kind of emergency has happened before off the coast of Barrow and other northern Alaska villages. In May 1997, rescue crews picked up 142 whale hunters from a floating ice sheet near Barrow after it cracked away from shore. That rescue effort lasted through the night and was complicated by fog, which made it difficult to locate the stranded hunters. Another rescue took place a couple of years ago on ice near Point Hope, Crosby said.

Sunday's rescue effort involved fewer people than the Barrow rescue five years ago and was aided by sunny, warm weather. It is unusual, however, because it happened so early in the year.

"I've never seen this happen in March, never in 50 years," Brower said.

No one knows what caused the leads to form, but Brower and Crosby guessed they may have been triggered by strong currents and a high tide. Brower also said the ice has been thinner than usual this winter -- about 4 or 5 feet thick instead of 10 to 12 -- because it did not form on top of old ice.

The leads soon widened to a quarter-mile or half-mile, Crosby said. Because the ice was breaking up so fast, time was of the essence.

"Those hunters might have been all right for a while, but you never know when the ice would start getting smaller and smaller," he said.

Some hunters didn't know they were in trouble. Jackie Nayakik, a seal hunter, said she didn't realize anything had happened until a helicopter landed on nearby ice to rescue her and six others hunting along the edge of the ice and the open water.

"They just came and got us and told us to get out," Nayakik said. "We were way far out and didn't know we were drifting away. We didn't hear anything or feel anything."

Price Ungarook, another seal hunter, had been hunting alone. He noticed one lead when he started back home. He had begun to try another route and was thinking about using his skiff when the helicopter landed near him. Like Nayakik, he was thankful for the ride.

"I can't walk on water," he said.