The slow-churning remnants of Tropical Storm Imelda that flooded parts of Southeast Texas left at least two people dead and rescue crews with boats scrambling to reach stranded drivers and families trapped in their homes. The relentless downpour drew comparisons to Hurricane Harvey two years ago.

By Thursday night, floodwaters had started receding in most of the Houston area, said the city's mayor, Sylvester Turner. Law enforcement officers planned to work well into the night to clear freeways of vehicles stalled and abandoned because of flooding, Police Chief Art Acevedo said.

But dangerous conditions persisted.

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Harris County Sheriff Ed Gonzalez tweeted about a morning drama:

We have an active search underway 27400 blk of Pleasure Ln. @HCSOTexas teammate was attempting to assist a citizen in high water and we’ve lost contact with him & the citizen. Praying for the safe recovery of both. I’m enroute to the area. #HouNews — Ed Gonzalez (@SheriffEd_HCSO) September 20, 2019

Later, Gonzalez tweeted that both were found safe.

Elsewhere in the area, at least two barges struck the I-10 San Jacinto River Bridge near Channelview, Texas, Friday, the Coast Guard said, adding that there were reports that nine barges broke away from their moorings at a shipyard.

CBS Houston affiliate KHOU-TV reported that I-10 was closed at the bridge as a result.

Officials fear the barges may have combustible materials in them and the bridge could be damaged. It will stay closed until it can be inspected, but the Texas Department of Transportation told KHOU that can't happen until the water level goes down.

A flash flood watch was still in effect through Friday morning for the Houston metropolitan area and most of Southeast Texas, KHOU said.

A school bus makes its way on a flooded road on September 19, 2019 in Houston Thomas B. Shea / Getty Images

Officials in Harris County, which includes Houston, said there had been a combination of at least 1,700 high-water rescues and evacuations to get people to shelter as the longevity and intensity of the rain quickly came to surprise even those who had been bracing for floods. The storm also flooded parts of southwestern Louisiana. The Coast Guard carried out many rescues, CBS Beaumont, Texas affiliate KFDM-TV said.

More than 900 flights were canceled or delayed in Houston. Further along the Texas Gulf Coast, authorities at one point warned that a levee could break near Beaumont in Jefferson County. During Harvey, Beaumont's only pump station was swamped by floodwaters, leaving residents without water service for more than a week.

People walk through flooded waters of Houston road on September 19, 2019 as Tropical Depression Imelda dumps heavy rain Thomas B. Shea / Getty Images

Imelda's remnants Thursday led to the deaths of two men. A 19-year-old man drowned and was electrocuted while trying to move his horse to safety, according to a message from his family shared by KFDM and the Jefferson County Sheriff's Office. Crystal Holmes, a spokeswoman for the department, said the death occurred during a lightning storm.

A man in his 40s or 50s drowned when he tried to drive a van through 8-foot-deep floodwaters near Bush Intercontinental Airport in Houston during the Thursday afternoon rush hour, Harris County Sheriff Ed Gonzalez said.

KHOU said first responders did their best to rescue him. Harris County Sheriff's deputies dove into the water to try to save him, to no avail.

The National Weather Service said preliminary estimates suggested that Jefferson County was deluged with more than 40 inches of rain in a span of just 72 hours, which would make Imelda the seventh wettest tropical cyclone in U.S. history.

Even when Houston was finally rid of the worst, downtown highways remained littered with abandoned cars submerged in water. Thousands of other drivers were at a practical standstill on narrowed lanes near flooded banks.

"The water kept rising. It kept rising. I couldn't believe it," said Ruby Trahan Robinson, 63. She uses a wheelchair and had a portable oxygen tank while getting settled into a shelter at City Hall in the small town of China, just outside Beaumont.

"It rolled in like a river," she said.

Turner, the Houston mayor, evoked the memory of Harvey — which dumped more than 50 inches of rain on the nation's fourth-largest city in 2017 — while pleading with residents to stay put. City officials said they had received more than 1,500 high-water rescue calls to 911, most from drivers stuck on flooded roads, but authorities described a number of them as people who were inconvenienced and not in immediate danger.

Imelda is the first named storm to impact the Houston area since Harvey hovered for days and inundated the flood-prone Gulf Coast. That storm dumped more than 5 feet of water near the Louisiana border, and two years later, it looked in some places like Harvey was playing out all over again. CBSN Originals told the story of Harvey's impact on the community of Winnie, Texas, in the documentary "Thicker Than Water."

Now Winnie, a town of about 3,200 people 60 miles east of Houston, is flooded again. A hospital there was evacuated.

A massive Houston furniture store became a shelter for evacuees. Live television footage showed firefighters rescuing stranded truckers on major highways. On social media, people posted that water was quickly seeping into their home and asked for help.

Even as the storm weakened, Harris County officials warned that some of their 4.7 million residents might not see high waters recede in their neighborhoods until the weekend.

Following Harvey, Texas Gov. Greg Abbott ordered a report warning that punishing storms would become more frequent because of a changing climate. Scientists say climate change is responsible for more intense and more frequent extreme weather such as storms, droughts, floods and fires, but without extensive study they cannot directly link a single weather event to the changing climate.

Climate change skepticism runs deep among Republican leaders in Texas, and Abbott has said it's "impossible" for him to say whether he believes manmade global warming is causing the kind of disasters the state is telling residents to get used to. Earlier this year, Abbott approved billions of new dollars to fortify the Texas coast and reduce catastrophic flooding.

The flooding from Imelda came as Hurricane Humberto blew off rooftops and toppled trees in the British Atlantic island of Bermuda, and Hurricane Jerry was expected to move to the northern Leeward Islands on Friday and north of Puerto Rico on Saturday.