Rain showers caused flooding on roads in parts of Texas early on Saturday, an official said, after severe weather killed at least 21 people earlier in the week, prompting U.S. President Barack Obama to declare a disaster in the state.

Texas has endured record rainfall for the month of May. This week, flooding turned streets into rivers, ripped homes off their foundations, swept over thousands of vehicles and trapped people in cars and houses.

Obama signed a disaster declaration late on Friday to free up federal funds to help rebuild areas of Texas affected by the storms. No estimate has been given for the damage in Texas.

On Saturday, there were reports of vehicles stuck in flooded streets in Rowlett, a community of nearly 60,000 residents just northeast of Dallas, said National Weather Service Meteorologist Jamie Gudmestad.

Fast-moving water was reported over a road in Bridgeport, a town less than 60 miles (97 km) northwest of Dallas, and parts of Plano were hit with 2.82 inches (7.2 cm) of precipitation with some reports of flooding there, Gudmestad said.

She added that less than an inch of rain fell in other parts of the North Texas region, but it was enough to cause concern.

"Anything that falls to the ground, the ground is so saturated it's going to cause run-off," Gudmestad said.

The Weather Service had flash flood warnings in effect on Saturday morning for several counties in North Texas, including Dallas County.

In Wharton, about 60 miles (100 km) southwest of Houston, water has been rising steadily since Thursday when the Colorado River began flooding into the city and the mayor issued a mandatory evacuation order for about 900 people living nearby.

The nearby city of Rosenberg also ordered about 150 residents living near the Brazos River to evacuate by Friday night.

(Reporting by Alex Dobuzinskis in Los Angeles; Editing by Raissa Kasolowsky)