By Danielle Kaeding of Wisconsin Public Radio News - Friday, August 31, 2018

A father and three children — ages 3, 6, and 9 — died in a kayaking accident Thursday night near the Apostle Islands of Lake Superior. The mother is the sole survivor.

Authorities are withholding names pending notification of family members and investigation by the Ashland County Sheriff’s Office, and Ashland and Bayfield County Coroner’s Office.

Ashland County Sheriff Michael Brennan said his office received a call from the woman’s sister at 8:29 p.m. Thursday. She reported alarming text messages from her sister, who was vacationing with her husband and three children. The messages read "911" and "Michigan Island."

The family of five was kayaking to Michigan Island from Madeline Island. U.S. Coast Guard Master Chief said on the way their boat started taking on water, capsized and sank.

"The father tried to swim to Michigan Island with the children and the mother remained with the kayak," he said. "At some point, she got separated from the kayak."

Haraf said the mother showed signs of hypothermia when she was rescued by the nearby U.S. Geological Survey research vessel around 10 p.m.

Brennan said two children were located just after midnight. The father was found a short time later. The third child was discovered on the shore of Michigan Island around 10 a.m. Friday. The search was hampered by thunderstorms moving through the area.

Haraf said the family tried to call and text for help around 4 p.m. Thursday, but the message didn’t go through until much later.

"They apparently were not in an area with cell phone coverage, and then when the cell phone coverage became available is when the message got sent out," Haraf said.

Brennan said there was little more he could reveal until all family members were notified.

"They’re not from this area," Brennan said. "They are from Wisconsin."

The family was wearing life jackets.

Authorities are now trying to locate the kayak as part of their investigation "to see if there is any structural damage or anything that would’ve caused it to take on water and capsize," Brennan said.

Autopsies are planned for each of the four in Hennepin County on Saturday, Brennan said.

Multiple agencies searched the waters for around 12 hours, including the U.S. Coast Guard, the Wisconsin Department of Natural Resources, Bayfield Fire and Rescue, and the National Park Service.