Torrential rainfall in the Houston area left parts of several major roads underwater Wednesday morning, complicating travel during the early rush hour.

Former First Lady Barbara Bush was taken to Houston's Methodist Hospital Wednesday but Bush spokesman Jim McGrath says she had to wait for the flooding to subside , KHOU reports. Her husband, Former President George H.W. Bush, is also hospitalized.

Traffic cameras showed cars struggling to get around floodwaters on Interstate 45 with several lanes blocked at North Main Street. Some areas received upwards of 5 inches of rain in just six hours, with the biggest totals occurring on the southwestern side of town.

(MORE: Where Flooding Has Been Most Frequent in the U.S. )

Officials told the Associated Press that crews responded to at least 65 calls for high-water rescues Wednesday, mostly from drivers who got stuck on flooded roads. In southwestern Houston, a METRO bus became trapped in flood water, and a good Samaritan rescued the driver and two passengers , according to KTRK-TV. The man who performed the rescue was identified as Carlos Castellanos, the report added.

"A stalled front draped along the southeast Texas coast interacting with Gulf of Mexico moisture brought the torrential downpours to Houston early Wednesday," said weather.com meteorologist Chris Dolce . "More showers and thunderstorms are possible through Thursday morning before an area of low pressure pushes the front out of the region."

Most schools started late due to the flooding and students who were unable to make it in will receive an excused absence, according to KHOU.com.

At least one line of Houston's METRORail system suspended service due to the flooding .

MORE ON WEATHER.COM: Flooding in California, Nevada