A high water sign is submerged near Lake Bistineau in Webster Parish, Louisiana, on March 14. Reuters

Torrential rains in the southern United States left parts of Louisiana, Mississippi and Alabama flooded, highways blocked and schools closed Friday. ABC News reported areas of the states were getting up to three inches an hour, causing Louisiana Gov. John Bel Edwards to declare a state of emergency.

"We are in constant contact with local officials and first responders, and assistance is already on the move to affected parishes," Edwards said in a news release. "The most important thing to remember is to obey road signs and to constantly monitor the news for updates to ensure everyone’s safety. Every available resource will be used to assist citizens as this situation continues to unfold."

The downpour was far from over — the Weather Channel predicted rains would continue through Saturday morning. As it stood Friday, more than 5,000 people in Louisiana alone had lost power and at least five school districts had called off classes. "It's going to going to get a whole lot worse before it gets better," meteorologist Tom Moore said.

In Alabama, the National Weather Service issued an early-morning flash flood watch Friday along the Gulf coast, according to the Associated Press. Water had rendered several roads unusable in Baldwin County earlier in the week.

"We've got water in places we've never had it," Gerard Landry, the mayor of Denham Springs, Louisiana, told the Baton Rouge Advocate.

Though it said most of the Mississippi River would probably be OK with the extra water, AccuWeather continued to urge caution, comparing the storm over the south to a tropical storm in terms of speed and rain. It also urged people to make alternate plans for the weekend and keep themselves as safe as possible.

As a reminder: If you're driving and encounter a flooded road, the National Weather Service recommends you turn around. It notes on its website that just a foot of rushing water can move a car downstream. "It is NEVER safe to drive or walk into flood waters," the service advises.