Heavy rains that brought a flood threat to North and Central Texas will spread into South Texas on Sunday as a stalled cold front causing the downpours is reinforced by remnants of Hurricane Patricia, CBS News reported Saturday.

Much of the Texas heartland was under a flash flood watch early Saturday as the National Weather Service expected the Austin-San Antonio area to receive up to a foot of rain while already inundated sections of North Texas were expected to experience up to 7 more inches of rain.

More than four inches of driving rain turned roadways into waterways in parts of North Texas today.

In the latest sign of the floodwaters' impact, a Union Pacific freight train derailed in flooded North Texas, near Corsicana, where the tracks washed away. Two crew members who were on board escaped by swimming to safety.