HOUSTIN-- Houston may be hit with more thunderstorms Tuesday night.
Floodwaters still haven't drained in some neighborhoods. Boats went out again Tuesday to rescue folks who were stranded.
At least six people have drowned, all in their own vehicles.
The video CBS News showed last night -- of a man trying to swim to safety with the help of a reporter -- is a reminder of what can happen when you drive into a flood.
On Tuesday, emergency crews pumped out the murky floodwater from a Houston toll road, looking for a sunken car, and its driver.
One of those killed in the floods was 49-year-old Sunita Singh. Her car got stuck in an underpass.
Her husband Rajiv said she couldn't get out.
"Driving into high water in the middle of the city and there is nothing that could be done? It's a terrible loss," he said.
Monday afternoon, Houston Fire's Technical Rescue Team braved the swollen bayou to train in the kind of fast moving water that can trap drivers.
"They underestimate the power of the water and their ability to get across the water," said District Fire Chief David Swanson.
Everybody thinks they're gonna be able to get over?
"They do..and it can cost them their life," Swanson said.
Nationwide, 112 people were killed last year when their vehicles got trapped in rivers or flash floods.
In Florida, which leads the nation in the number of car crash drownings, the Collier County Sheriff's Department drove a car into the water to show people how to survive being submerged.
The first 30 to 60 seconds are the most crucial, they say.
The first step is to undo seat-belts.
Then, open or break the car window.
Afer that, get children out of the car as fast as possible, starting with the oldest.
Then adults should get out.
It's a lesson that, that Houston driver learned first hand on live television.
Emergency crews are still pumping water from an underpass, and have found an SUV.
The person inside is the 7th person who drowned in their car in this storm.