HOUSTON, TEXAS:  At least six persons, including an Indian-American woman, were killed in “historic” flash flooding in Houston, submerging of scores of subdivisions and several major interstate highways and forcing the closure of schools.

Sunita Singh, 47, senior electrical engineer at Bechtel Oil & Gas was found dead in her car Monday during the flash floods that killed six people

She was going to work as usual at 6:30 am, her husband Rajiv Singh told the media. Since the exit was closed she drove to another one. Around 6:50 am she called her husband saying that the water was rising. She thought rescue workers were around, but there was none.

Rajiv Singh continued to call her with no reply.

She is survived by her husband and 15-year-old son.

One of the victims was found in a submerged 18-wheeler cab on the N Beltway 8 frontage road near the Hardy Toll Road. Two others were found in separate vehicles.

In Waller County, a 56-year-old Royal ISD teacher was found inside a submerged vehicle off Adams Flat Road.

More than 470 flights were cancelled at Bush Intercontinental and Hobby Airport in the morning hours.

An overnight storm dumped between 8 and 16 inches of water on the area. The heavy rainfall also closed local schools, knocked out power for more than 121,000 residents and made many roadways impassable.

More than 1,200 high water rescues have been reported by Houston and Harris County officials. Officials in Harris County have declared a disaster area and estimate at least 1,000 homes have already been flooded. More than half the watersheds in Harris County are experiencing significant flooding, with least one cresting above its estimated 500-year flood mark, a new all-time record.

The local National Weather Service (NWS) has warned residents not to travel “unless you are fleeing an area subject to flooding or under an evacuation order.”

About 120,000 homes are without power, and school and transit systems are shut down across the region.

“Houston is in the midst of an unbelievable deluge, with already more rainfall in a single day than any hurricane to ever hit the hurricane-prone city. The flooding is “historic”, NWS said in a statement.

The City of Houston closed city offices, including municipal courts, and has told non-essential employees to stay home for the day.