Despite receding floodwaters in Texas and Oklahoma, dangers can persist as residents begin the process of cleaning up the mess left behind.

At least three people were killed in Texas and many more injured as floodwaters hit the state Monday night.

Bristel Minsker, spokeswoman for American Red Cross, said a big risk for residents is that remaining floodwater can be toxic after washing over roads and even bringing cars and other debris along.

"The Blanco River overflowed and it’s been running through the state and pushing all this debris down through the state," said Minsker, who called the water extremely toxic.

Members of the Houston Fire department help residents evacuate through the floodwaters surrounding their homes in Houston, May 26, 2015.(David J. Phillip/AP Photo) Members of the Houston Fire department help residents evacuate through the floodwaters surrounding their homes in Houston, May 26, 2015.

Minsker said it's important to keep young children and pets away from the water so they don't ingest any of it. For people who had to wade through dirty water to get to safety, Minsker recommends immediately showering and washing clothes to get out any toxins that were washed into the water during the flood.

Minsker said residents should only return home after officials have given the all-clear and always check for downed power lines, foundation cracks or broken gas lines before entering the home.

She also said any food that comes into contact with floodwaters, even bottled water or canned goods, needs to be thrown out.

Another unexpected hazard for those returning home: wildlife.

"We’re hearing a lot of reports of snakes getting washed on to people’s property," said Minsker, who warned that people should stay far away because the animals might be panicked or aggressive.

"They’ve been driven from their natural rural home. It’s an area they are not comfortable with," she said.

A man walks past a cabin that was torn from its foundation in a flood on the Blanco River days earlier, May 26, 2015, in Wimberley, Texas.(Elaine Thompson/AP Photo) A man walks past a cabin that was torn from its foundation in a flood on the Blanco River days earlier, May 26, 2015, in Wimberley, Texas.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said as residents are able to clean up more and more, there will be other issues they face including mold or dust that can exacerbate asthma or breathing problems.

"You can get mold growing up on things that you’re then trying to clear out," Schaffner said.

Murphy Canning and Annika Rolston watch as a street remains underwater from days of heavy rain on May 25, 2015 in Austin, Texas.(Drew Anthony Smith/Getty Images) Murphy Canning and Annika Rolston watch as a street remains underwater from days of heavy rain on May 25, 2015 in Austin, Texas.

Minsker of the Red Cross said it's key for residents with a flooded home to add fans or dehumidifiers to try and keep the mold from growing and causing health problems.

Also, as mud dries it can turn into dust that affects the lungs, said Dr. Schaffner, who recommends wearing a surgical mask.

Schaffner said anyone who had a wound exposed to floodwaters should seek medical attention to see whether they should get a tetanus booster shot.

In addition to short-term problems, Schaffner said, there's another hazard that could last long after the floodwaters recede. He said he's concerned that standing water could mean in increase in the West Nile virus carried by mosquitoes, especially as summer approaches.

"All this floodwater is going to leave puddles and pockets of water that will be great breeding grounds of mosquitoes," Schaffner said. "If there are a lot of mosquitoes, more mosquitoes will bit birds and then bite people," spreading the virus.

The Texas Department of Health has a full list of recommendations on flood safety here.