Dozens of people searched a swollen river in eastern Wyoming by land, water and air Friday for a sheriff's deputy who disappeared after entering the water the previous evening to try to help a struggling girl.

Converse County Deputy Bryan Gross, 29, went into the North Platte River at about 5 p.m. Thursday, Undersheriff Don Schoenleber said. He entered the river near the Douglas Yellowstone Bridge, which joins both sides of the town of Douglas, 50 miles east of Casper.

"The deputy went into the river to facilitate the rescue of a juvenile female," Schoenleber said.

Other emergency workers recovered the girl about a mile downstream Thursday evening and took her to a hospital.

Schoenleber declined to identify the girl.

Searchers continued to look for Gross until nightfall, Schoenleber said. Deputies used lights on area bridges to scan the river overnight to keep watch for Gross.

Schoenleber said 30 to 40 people, including some using boats and aircraft, resumed the search at 6 a.m. Friday. He said searchers were walking the riverbank, with some using tracking dogs.

A dispatcher at the Converse County Sheriff's Office said shortly before 10 a.m. that there were no developments in the search.

The North Platte River near Douglas is higher than normal following heavy snows last winter.

Deputy State Engineer Harry C. LaBonde said the river was running at 6,620 cubic feet per second Friday at a nearby gauging station, downstream from Douglas. He said the flow averaged only 2,110 cfs on the same date over the past 60 years.

"It's higher than you would expect this time of year based on the water we're having with all of the snow and the releases from all the federal reservoirs," LaBonde said.

There have been several deaths in Wyoming this year associated with flooding and high water, including four members of a Colorado family killed earlier this month when a highway washed out in a heavy rainstorm.

President Barack Obama last week declared a major disaster in Wyoming because of spring and summer flooding. The declaration opened the way for the federal government to help the state pay for costs incurred from damaged roads, highways and other infrastructure.