Harvey's catastrophic flooding moved east of Houston on Wednesday as the storm continued through southeastern Texas into Louisiana.

Over 26 inches of rain were recorded at the airport near Port Arthur, a city located about 90 miles east of Houston in Jefferson County, on Tuesday alone. The rainfall triggered flash flooding that many residents of the area were desperate to escape.

The Bowers Civic Center, where at least 100 people had sought shelter after their homes flooded, was inundated with water early Wednesday morning. Evacuees were forced to abandon floating cots and retreat to the bleachers lining the building.

Other shelters have since opened in the city to accommodate the approximately 3,000 evacuees who needed a place to stay.

Port Arthur mayor Derrick Freeman told CBS News that 20,000 homes had as much as 6 feet of water in them. Jefferson County Deputy Sheriff Marcus McLellan said 911 operators had gotten overwhelmed with requests and residents were in "survival mode."

Freeman posted on Facebook Wednesday afternoon that the US Coast Guard, local first responders, and volunteers had more than 150 boats out rescuing people.

"Our whole city is underwater right now but we are coming! If you called, we are coming," Freeman posted on Facebook early Wednesday morning. "Please get to higher ground if you can, but please try stay out of attics."

Check in #PortArthurTexas Posted by Derrick Freeman on Wednesday, August 30, 2017

The Port Arthur city Twitter account encouraged residents to "display a white towel, sheet, shirt or anything" so rescuers could find them in the torrential rain, which was still pouring down Wednesday afternoon.

Hal Needham, a hurricane scientist at Louisiana State University, estimated in a blog post that the triangle of Port Arthur and Beaumont in Jefferson County and Orange in the neighboring Orange County was getting as much as 6 inches of rain an hour. The Weather Channel reported that Port Arthur was receiving up to 3.87 inches an hour.

"I promise I am not exaggerating when I say at least hundreds, if not thousands, of people are fighting for their lives right now," Needham wrote Wednesday morning.

People in the area posted hundreds of messages on Facebook and Twitter requesting rescue:

Freeman said multiple fires broke out Tuesday night, and the Port Arthur Fire Department lost three firetrucks in the carnage.

Officials closed the I-10 highway from Houston to New Orleans because the floodwaters were so high. And the Motiva oil refinery in Port Arthur, the largest in the US, was forced to shut down because of the flood, CNN reported.

Livestock were also caught in the floodwaters, and the Texas Department of Transportation posted a harrowing video of cattle running down a flooded highway:

"We aren't hearing these people crying out because they have no voice," Needham wrote. "Many have lost power, in the best case have made it to a roof. The eyes of the world are on Houston and these smaller cities in southeast Texas are crying out and nobody can hear them."

The rain in Port Arthur should let up by Wednesday night.

"Continue to pray for us; lift us up," Freeman said in a Facebook live video Wednesday afternoon, adding, "We're tough. We're going to rebuild. We're going to bounce back even stronger than we were before."