Tropical Depression Imelda dumped catastrophic amounts of rain on parts of eastern Texas and western Louisiana overnight—and forecasts show the deluge of water isn’t over yet.

The unrelenting flooding has stranded hundreds of people, requiring water rescues, evacuations, and desperate calls from police for people not to attempt to drive their way to dry ground.

The National Weather Service says driving a vehicle into floodwaters is the “single worst decision you can make in a flash flood,” due to the unknown depth and deceptive strength of the current.

Harris County Sheriff Ed Gonzalez announced what appeared to be the first flood-related death late Thursday, saying a driver who had driven into 8-foot high floodwaters in Houston was later pulled out of his vehicle after it was too late to save him.

“We’re sad to report that an adult occupant, extracted from the submerged van, has been pronounced deceased at the hospital. It remains unknown if the male was the only occupant in the van,” Gonzalez tweeted. Authorities were searching for any other possible victims at the scene.

The cities hit with the most flooding so far are some of the very same areas impacted by Hurricane Harvey in 2017, putting people who only just rebuilt their homes back in a flood zone.

Vidor, a city of over 10,000 people northeast of Houston, is still under a flash flood warning, and Police Chief Rod Carroll has said the rainfall is already worse than during Harvey two years ago, which became most extreme rain event in United States history.

“This didn’t happen to us during Harvey, and also this came out of nowhere,” Mo Danishmund, chief financial officer for Riceland Healthcare, a hospital in Winnie, Texas, where evacuations were taking place after the facility was swamped by more than four inches of water told The Houston Chronicle. “[This] is worse than Harvey.”

Houston Mayor Sylvester Turner has instructed residents on Twitter that if they are in a safe place, such as in an office building or in a school, to “please stay put for the next 3-4 hours and allow the weather system to clear our area.”

In neighboring Beaumont, Texas, a city of 120,000 people about 30 miles from the Gulf of Mexico, there have been over 590 flood-related emergency calls, including 250 high water rescues and 270 evacuation requests, according to police.

Exxon Mobil shut down its chemical plant in the city, and said it is closely monitoring its oil refinery on the same site. The refinery is the fourth largest in Texas, and is currently undergoing a major expansion that will make it one of the two largest refineries in the country. “Exxon Mobil’s Beaumont refinery and chemical complex is conducting a preliminary assessment to determine the impact of the storm,” an company spokesman told the Chronicle. “The Beaumont chemical plant has completed a safe and systematic shutdown of its units.”

Officials are telling residents to shelter in place and get to high ground if possible. All service roads in the city have become impassable, leaving two local hospitals inaccessible, according to authorities.

“It’s bad. Homes that did not flood in Harvey are flooding now,” said Jefferson County Judge Jeff Branick.

Beaumont police spokesperson Carol Riley said authorities are in “strict life-saving mode right now.”

“Let the public know more than anything stay off the roads. Shelter in place,” Riley told the Beaumont Enterprise. “People are panicking because they have ankle deep water in some places or their cars are stalling.”

According to the National Weather Service, Imelda is moving slowly across the region and an additional six to 12 inches of rain—on top of the 30 inches so far reported in parts of Texas—could fall through Thursday night.

The Jefferson County Sheriff’s Office has issued a warning that a levy holding back 4,600 to 5,600 acres of water from flooding 219 area homes, Interstate Highway 10, and thousands of agricultural acres has deteriorated to the point that it “could break any moment.”

Residents of Gilbert Lake Estates near the Green Pond Gulley Levy have been ordered to evacuate immediately.

“Rescue Boats are sparce (sic) at the moment however, we do have several en route to that area,” reads a warning posted to the sheriff’s office’s Facebook page. “If you live in the area and have a boat, please pick up your neighbors and go to Hwy 365 overpass at I-10.”

The levy was also breached during Hurricane Harvey. A multi-million dollar Hurricane Harvey restoration project approved in 2018 has worked to stabilize the basin. The USDA-Natural Resources Conservation Service of Texas reported in August 2018 that a “26-foot deep washout in the bottom of the levee” was repaired and that the remaining work of stabilizing the embankments eroded away by flooding would be completed by the drainage district.

“The levee was built for a 500-year flood, but some estimate this was a 1,000 plus year flood,” said Richard LeBlanc, Jr., general manager of the Jefferson County Drainage District, after Harvey’s flooding. “... We have spent a lot of time and money to protect our area. We repair the damage and hope we never have this type of historic rain again.”