GRAYSON COUNTY, TX -- June of 2007 marked one of the worst floods this area has ever seen.
Sherman Police Sgt. D.M. Hampton said many people don't realize that even a few inches of water can carry a current - which can easily sweep away a vehicle.
"And it ends up turning over," he said. "And ends up trapping the people inside the vehicle."
He said flash flooding can happen with little warning.
"I've seen where water has been moving on a city street and eroding some of the underneath, and it looks like it's only two or three or four inches deep, and there's a big rut underneath that someone may hit," he said.
As the season progresses, some of the creeks that run through town will clog with sticks and other debris, which make them more likely to flood, Hampton said.
Sarah Somers, Grayson County emergency manager, urges residents to sign up for emergency alert phone calls - especially since flooding happens with little warning.
"We sadly lost some of our residents in June of '07," she said. "And those folks were on their way to work, because they hadn't gotten word about how hazardous it was."
And she said families should come up with a communication plan - especially if phone lines are jammed.
"To make sure that they know that they're safe and well," she said. "So by texting, and posting on social media counts."
Hampton said if you see standing water, it's best to always play it safe.
"You just need to go around," he said. "Turn around, don't drown."
During floods, drivers should be aware of cop cars with their lights on - they're usually warning you to stay away from that particular stretch of road, Hampton said.