A 7-year-old child drowned in Michigan's Flint River over the weekend and authorities are searching for a second child who has been presumed dead after falling into the river the following day.

The first child, a 7-year-old boy who has special needs, wandered away and drowned in the Flint River Saturday, Genesee County Sheriff Chris Swanson told USA TODAY.

The next day, a 6-year-old girl wandered away and was spotted in the river, the sheriff confirmed to USA TODAY Wednesday afternoon. The sheriff's office previously announced an incorrect age for the girl.

"We had back to back child drownings within 24 hours on the same river, two different parts of the city and both of them are fatalities," Swanson told USA TODAY.

Flint Fire Chief Theron Wiggins said in a statement provided to USA TODAY that he is “deeply saddened” by the death of the 7-year-old child in the Flint River on Saturday.

“I want to remind our community that playing near the Flint River is dangerous due to hidden debris and strong currents,” Wiggins said. “As the weather warms, I encourage families to be safe while enjoying the natural resources and parks in Flint.”

6-year-old and another child slid down into river: Sheriff

Swanson said the 6-year-old girl was with a 9-year-old around 5:15 p.m. Sunday when the pair wandered from their home.

"There's cement banks that go at a 40 degree angle into the river," he said. "They're probably 30 feet long into the river. Well, they slid down that cement bank into the river. The 9-year-old was able to climb out and the 6-year-old is the one that we're looking for."

When authorities spotted the girl, the river was moving five to eight miles per hour and looked "very murky," he said. By the time searchers were deployed into the river, she had gone underwater and it was clear to authorities that the case had become a recovery, not a rescue.

"Since then, we've deployed 75 to 100 staff and volunteers per day," he said. "We have a dive team group that is made up of southeastern Michigan counties ... approximately 14 counties that have brought the best technology that we possibly have. We've dropped the river 18 inches by shutting down two dams upstream."

He said the crew is waiting to see if she'll surface.

“The problem with this river is it's so dangerous and it's filled with hazards, trees,” Swanson said in a video posted to Facebook on Monday.

He said the river contains water that goes under the banks, making way for a body to rest. He said the fact that there’s moving water present also makes things difficult. As he filmed the video, the water didn’t look dangerous, he noted, but the undertow is still there and poses a threat.

“One of our sergeants actually saw the victim yesterday, distant with a little pink shirt, so we knew that this was the starting point,” he said in the video on Monday.

The same crew responded to both incidents, Swanson told USA TODAY. Having two apparent drownings in one weekend is “heavy” for everyone involved, the sheriff said.

“Hug your family,” he said. “Love your family.”

Saleen Martin is a reporter on USA TODAY's NOW team. She is from Norfolk, Virginia – the 757. Follow her on Twitter at@SaleenMartin or email her at[email protected].