Updated

As devastating flooding spawned by Tropical Storm Harvey inundates portions of the nation's fourth-largest city, Houston's downtown showcase convention center is now serving a different role as an emergency center.

Officials opened up the George R. Brown Convention Center Sunday as more than 24 inches of rainfall pummeled Houston, stranding motorists on area highways and forcing residents to their roofs to be rescued from floodwaters.

Houston police Chief Art Acevedo said authorities have rescued 2,000 people from flooding, including 185 critical rescue requests still pending as of Monday morning. The goal is to rescue those people by the end of the day, according to Acevedo.

Convention Center 2

People seek shelter from the aftermath of Hurricane Harvey at the George R. Brown Convention Center in Houston on Sunday, Aug. 27, 2017. (Elizabeth Conley/Houston Chronicle via AP)

FEMA Administrator Brock Long, who called the flooding a "landmark event," said Monday morning officials are anticipating over 30,000 people being placed in shelters temporarily.

"This is still an ongoing situation," Long said at a news conference. "We're not at recovery yet."

Massive dump trucks that plucked people from flooded homes delivered them downtown, where the American Red Cross is set up. The main facility is one of the many shelters in Houston, which include churches, schools, and even some furniture stores, according to FOX 26 Houston.

Gallery Furniture is also welcoming area residents in need of shelter to a location off Interstate 45, and is stocked with food, water, plenty of mattresses  FOX 26 reported.

Convention Center 3

Terranysha Ferguson holds her son, Christian Phillips, as she sits with the rest of her family at the George R. Brown Convention Center in Houston on Sunday, Aug. 27, 2017. (Elizabeth Conley/Houston Chronicle via AP)

"Houstonians have a safe, dry place to take shelter at Gallery Furniture so if they can get here they are welcome," said owner Jim "Mattress Mack" McIngvale. "We hope to give them some comfort in this incredibly difficult time."

The Red Cross mobilized at the downtown convention center on a few hours' notice, said Ken Sandy, a shelter manager. The city of Houston had publicly announced just two shelters Saturday night, as the worst of the rain that pelted Houston and surrounding Harris County began. One of the shelters had to close because it was too close to high water.

Houston Mayor Sylvester Turner then announced Sunday morning that the convention center would become a shelter. A few hours later, the first group of evacuees arrived.

"We're just getting people together to get some rest, get a meal, and think about what we're going to do for recovery," Lloyd Zeil with the the American Red Cross told Fox News.

HARVEY FLOODING FORCES NEW EVACUATIONS, AS HOUSTON BRACES FOR MORE RAIN

As of Monday morning, around 2,500 people are at the convention center, which has enough space and cots to house 5,000 inside. The center also was used as a shelter for Hurricane Katrina refugees in 2005.

Many arrived Sunday carrying little more than what was in their pockets and were preparing for a stay of several days, as water rises inside their homes and roads remain impassable.

Patricia Cain, her son, William, and 9-year-old grandson were among hundreds of people who arrived Sunday by boat, by bus, and by foot at the convention center.

Convention Center 1

D'Ona Spears, center, reacts as she is told that she cannot bring her dog Missy into the shelter for flood evacuees with her daughter Natalie, left, at the convention center in downtown Houston, Texas, Sunday, Aug. 27, 2017 (AP Photo/LM Otero)

"I live in a lake where there was once dry land," William Cain told the Associated Press.

Weary and carrying little more than what was in their pockets, they prepared for what could be several days inside the convention center.

Inside a cavernous hall humming with the sound of hundreds of conversations, volunteers served food, handed out towels and set up tables with donated clothes for a long line of evacuees. Some people huddled around a projection screen showing television coverage of the storm, while others collected bowls of pasta with parmesan cheese and cups of black coffee.

"We need to make sure folks have a place to go, the shelters around town, around Texas," Zeil told Fox News. "We're all going to get through this together."

A long line of people carrying blankets and pillows waited to enter a separate space in the convention center serving as the dormitory.

Many of those at the shelter were from the Clayton Homes, a public housing complex bounded on one side by an interstate highway and another by Buffalo Bayou, which flooded heavily along with all of Houston's major waterways.

Police used boats to evacuate many of the complex's residents and bring them to the convention center in trucks.

D'Ona Spears and Brandon Polson walked with their five children, bags full of belongings, and their 7-year-old Chihuahua, Missy. They decided to leave once the water in the first story of their home reached their knees. Polson said the management at the complex wouldn't open a community building on site that had stayed dry as the apartments around it were flooding.

"As soon as you step out, a lot of cars are in the water," Spears said.

VOLUNTEERS SAVE HOUSTON FAMILIES IN SUBMERGED HOMES

Alex Cantu Jr. rode out the storm underneath a bus shelter. Cantu, 50, said Sunday that he was waiting for a bus to the Salvation Army shelter where he lives, but buses were canceled. The flooding made it too dangerous for his brother to pick him up. So he and a few other people slept in the bus shelter.

"I was soaked cold," he said.

On Sunday morning, his brother told him he could go to the convention center, where he hoped to stay through the duration of the storm.

"I don't know how long they're going to let people stay," he said, a white towel draped around his shoulders. "My brother said it would be over Wednesday."

The Associated Press contributed to this report.