PHOENIX (Reuters) - Two children were found dead and another was missing in Arizona on Saturday after the vehicle they were in became stuck while crossing a storm-swollen forest creek outside Phoenix, part of a post-Thanksgiving winter storm that pummeled wide swathes of the country.

The storm system has been slowly moving eastward across the United States, clogging the Midwest with snow and disrupting flights on the busiest travel weekend of the year.

The children were reported missing late Friday afternoon after a vehicle got stuck in Tonto Creek near Tonto Basin, northeast of Phoenix, the Gila County Sheriff’s Office said in a statement.

Rescue workers in helicopters successfully reached four other children and an adult who were stranded on an island in the creek and a second adult who was on the shore. A search was launched for the three missing children.

Two of those children, a boy and a girl, both about 5 years old, were found dead on Saturday about three miles downstream from where the vehicle became submerged, said Virgil Dodd, a sheriff spokesman.

About 30 first responders were still searching for the missing girl.

“We hope we find the last one and bring her to safety,” Dodd said.

The two adults were parents of four of the seven children involved in the incident. Dodd said the group was believed to be from out of town, but no details were known.

The group was in the area for a family reunion during the U.S. Thanksgiving holiday, the KPNX news channel reported.

Blizzards and deep snowfalls were forecast for much of the Midwest and Northeast for the rest of the weekend as millions of Americans travel home from their holiday feasts, the National Weather Service said.