Update, 3:15 p.m.: Authorities in Hays County in Central Texas say they're trying to locate more than 40 people after the heavy rain and flooding.
The count includes a dozen people witnesses say they saw in floodwaters. The rest could be staying somewhere else or just aren't home. At least two people are confirmed dead.
Elsewhere in Texas, Houston emergency managers say nearly every part of the city is affected by floodwaters. Crews have made more than 500 water rescues since Monday night and drivers seeking higher ground have abandoned thousands of cars and trucks on city streets.
Update, 1:50 p.m.: Authorities say two people have died in Central Texas due to flooding.
One person died in San Marcos and another died in Caldwell County. Hays County emergency coordinator Kharley Smith said at a news conference Tuesday that the Blanco River rose by 12 to 14 feet in a 30-minute period yesterday. Hays County is about 35 miles southwest of Austin.
Thirty people are unaccounted for, though some may be staying elsewhere. Eight of those missing were in a vacation home that was swept down the river and slammed into a bridge.
Hays County Commissioner Will Conley says 70 homes were destroyed and 1,400 homes and properties have some type of damage after this weekend's torrential rains.
Virtually every part of Houston has been affected by floodwaters, emergency management coordinator Rick Flanagan said, most notably central and southwest Houston.
He said Tuesday that fire crews responded to about 530 water rescues overnight, mostly from people stranded in their vehicles.
At least 2,500 abandoned vehicles are strewn about the city from drivers seeking higher ground.
Flanagan says the priority is clearing the vehicles and debris. He says about 50,000 residents were without power late Tuesday morning, down from the 150,000 around midnight.
Original post: Three people were found dead this morning in Houston after floodwaters swept the area.
Authorities say two bodies were found in the city, while another was found in a vehicle on Interstate 45.
The Houston Chronicle reports firefighters made at least 131 water rescues overnight. Most were calls from stranded motorists.
High water has made driving almost impossible for many throughout the city. About 11 inches of rain have fallen in parts of the Houston, leading to the widespread flooding. Between 500 and 700 homes have sustained some level of damage.
Houston METRO announced that the morning transit services were canceled. Harris County district courts canceled morning jury service. Storms also knocked out power in parts of the city.
About 20 school districts in the area were either closed or had a delayed start time.
Floodwaters are receding in Austin, but KUT reports the city could see more rain and thunderstorms this week. High water levels there have caused untreated wastewater runoff. The city has warned residents near runoff sites to boil water before using.
Video: Houston Under Water
Rice University shot this footage of the flooding in Houston.
The Associated Press contributed to this report.