(CNN) -- Rain-soaked Houston was getting no respite from the weather Tuesday, April 19, 2016 with a flash flood watch extended through the morning and the possibility of thunderstorms all day.
At least five people were killed in what one official called the most significant flood event since devastating Tropical Storm Allison in 2001.
Texas Gov. Greg Abbott declared a state of disaster in nine counties in and around the Houston area.
Thousands without power
Abbott advised residents to exercise caution amid the weather. Though rain was falling over the entire region early Tuesday, the city planned to take advantage of a predicted lighter rainfall and begin the cleanup, said Janice Evans, the spokeswoman for Houston's mayor.
"City already putting together debris collection schedules," Evans tweeted.
The regional utility CenterPoint Energy restored power to more than 100,000 people Monday, it reported on its Twitter page -- but 20,000 people were still in the dark, and crews planned to work through the night to turn the lights back on.
'Turn around, don't down'
Monday's flooding made for some dramatic rescues, including a man who was seconds away from being submerged.
Just before a news crew from CNN affiliate KTRK was about to go on air at the edge of a flooded road, they saw the man's black Toyota Prius drive into the water and quickly float away.
The man opened the door and Reporter Steve Campion yelled for him to get out of the car.
"You gotta get out!" he yelled. The man hesitated as Campion yelled, "Swim! Swim! Leave the car. Swim!"
The man finally swam toward Campion, and as the reporter helped him onto dry land, the car disappeared beneath the water.
Campion said later, "It certainly is a reminder to turn around, don't drown. We say that in Houston so often, but you really never know how deep the water is."
Horses rescued
North of Houston, more than 70 horses had to be rescued when flood waters rose too quickly for their owner to evacuate them.
"We woke up around 3 and it was already too high to get the trailers out," said Darolyn Butler, owner of the Cypress Trails Equestrian Center in Humble.
"All we started doing was just trying to move horses to high ground, and we had one pasture that we thought was safe (but) they broke out and got in the water," she said.
The horses became stranded all over the nearby woods. It was a multi-person effort to get each one out, with cheers going up each time the horse reached land.
None of the animals died, KTRK reported, citing the Office of Emergency Management.
Billions of gallons, billions in damage
Emmett said Monday afternoon he estimates 240 billion gallons of rain has fallen in the Houston area. He called it the most significant flood event since Tropical Storm Allison in 2001, which left 41 people dead. It caused more than $5 billion in property damage in Harris County alone, according to the county's Flood Control District.
At the Royal Phoenician apartment complex in north Houston, the brown floodwaters submerged cars in the parking lot early Monday, a resident said. He posted video to Twitter later showing the waters had gone down slightly, though levels still reached car windshields.
Another north Houston resident posted video of residents leaving their flooded homes in a canoe as the rain continued to fall.
The storm snarled air traffic. About 800 flights were canceled Monday at George Bush Intercontinental Airport and nearly 200 at Hobby Airport, but the airports said flights were resuming by the evening.
The heavy rains forced seven of the city's many bayous out of their banks and created flooding in parts of the city that had not flooded for many years, Houston Mayor Sylvester Turner said.