HOUSTON — The water came in the middle of the night “and it just kept rising.”

That’s how family after family described the chaos that forced thousands to flee their homes and take refuge Monday at the George R. Brown Convention Center in downtown Houston.

In the middle of the expansive exhibit hall, some sat wrapped in American Red Cross blankets with their eyes glued to a large screen, unable to look away from TV reports that described the damage to their homes, neighborhoods and lives as Tropical Storm Harvey continued to dump unprecedented amounts of rainfall on the nation’s fourth largest city.

Displaced South Houston residents Oralia Guerra and Diamond Robinson huddle together to stay warm underneath Red Cross blankets at the George R. Brown Convention Center in Houston on Monday. Floodwaters reached the rooflines of single-story homes Monday and people could be heard pleading for help from inside as Harvey poured rain on the Houston area for a fourth consecutive day after a chaotic weekend of rising water and rescues. (Louis DeLuca / AP)

“It was a journey,” said Claude Green, whose family of five lives in northeast Houston. There was little rain when he went to bed Saturday night after watching the Floyd Mayweather-Conor McGregor fight.

“But when we woke up, it was up to my chest.”

He and his wife Stephanie grabbed a bucket and an inflatable swimming pool, and floated their daughters a half mile through rising waters. A man in a boat got them to waist-deep water.

Another man, in an 18-wheeler, got them across Greens Bayou — one of the many waterways that contribute to Houston's Bayou City nickname.

A dump truck picked them up from there and took them to a church. They stayed overnight before being driven with a busload of other evacuees to the convention center, where more than 3,800 people were already sheltering by midday Monday.

1 / 10Merci Green (right) and her sister, Evella Green, rest in the arms of their father, Claude Green, as they wait to go into the Red Cross shelter at the George R. Brown Convention Center in Houston on Monday. The family was evacuated after their home flooded in northeast Houston.(Louis DeLuca / Staff Photographer) 2 / 10Signs show the way for the Red Cross shelter at the George R. Brown Convention Center in Houston. (Louis DeLuca / Staff Photographer) 3 / 10Red Cross workers try to route the crowd into the main area for evacuees at the George R. Brown Convention Center in Houston on Monday. (Louis DeLuca / Staff Photographer) 4 / 10Displaced Houston residents sort through tables filled with used clothing at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer) 5 / 10Displaced South Houston residents Oralia Guerra and Diamond Robinson huddle together to stay warm underneath Red Cross blankets at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer) 6 / 10A man dressed as Batman shakes hands with people as they arrive at the Red Cross shelter at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer) 7 / 10Red Cross worker Katrina Dirscherl talks with Oralia Guerra and Diamond Robinson as they huddle together to stay warm underneath Red Cross blankets at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer) 8 / 10Houston residents bused in from the northern part of the city arrive for shelter in the driving rain at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer) 9 / 10Displaced resident Darnyl Thomas plays with his daughter, Riley Thomas, as they try to pass the time at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer) 10 / 10Houston Mayor Sylvester Turner talks with officials before a press briefing at the George R. Brown Convention Center in Houston on Monday.(Louis DeLuca / Staff Photographer)

Rain was still pouring when the Greens arrived downtown to the shelter that was expected to swell to more than 5,000 people by nightfall. A Red Cross volunteer setting up chairs looked across the room as incomers seeking safety piled up at the entrance.

"Oh my God," he said.

Elsewhere in the convention center, dozens of large, round, fold-out tables lined a wall. The smell of chili filled the hall around noon. Some sat quietly and ate. Others charged their phones and devices and shared stories.

On the opposite side of the room — past hundreds of sleeping, lounging, crying or anxiously pacing evacuees — a makeshift medical center was being expanded.

“What’s your issue today?” asked a nurse. The elderly woman with silvery hair braided into neat cornrows couldn’t hear well enough to respond.

Nearby, a man in a hospital gown and bandages on his legs stared into the distance. Asked if he was okay, he responded in one word. “Diabetes,” he said. He hadn’t taken his insulin in a day.

Green said he and his family felt fortunate. "A lot of people were still over there, on their houses," he said.

At a bayou several miles south of where the Greens live, others also awakened over the weekend to water overtaking their homes.

Shelia Opot woke up Saturday to a barrage of texts from her brothers, also Houstonians, who had seen reports about her neighborhood on the news. She told them she was fine.

“But I had not gone downstairs,” she said. “When I did, my place was flooded.”

Within an hour, the water rose from her ankles to her knees. “It was just rising, rising, rising,” she said, her hands motioning to indicate where the water levels reached.

Then the power went out.

Like hundreds of others seeking rescue teams in the Braeswood area of southeast Houston, one of the worst-hit areas, she called 911.

“Nothing. It was busy,” she said. So she pleaded for help on Nextdoor, an online neighborhood bulletin board.

“We’ll get you out of there. Stay put,” responded a neighbor who arrived an hour later in a canoe. “I was so, so, so scared. And I didn’t want to show fear,” she said, wanting to be strong for her kids.

Opot sat with her kids huddled in blankets around her. Behind them, a volunteer had rounded up about a dozen small children, who laughed and giggled as the man wearing a Brown’s Gymnastics T-shirt taught them headstands. Parents stood or leaned on the wall nearby, looking relieved for the reprieve. They were happy to be safe. And together.

For four grueling hours Sunday evening, Maha Alghwaini, an Iraqi refugee who has lived in Houston for nearly five years, didn’t know where her children were.

She sat alone, in the back of the shelter near the makeshift clinic in which the term “Medical” had been handwritten on orange sheets of paper. Ahead of her were lines of men, women and children picking up necessities: toothpaste, socks, blankets, diapers.

She became separated from her 10-year-old daughter and 12-year-old son as rain poured on them from their neighbor’s third-floor patio at the Meyergrove Apartments off Braeswood Boulevard.

Her children were put on a boat, and air rescue had to come back for her 15 minutes later.

But when she got to the school buses lining up to bring evacuees from her neighborhood to the convention center, “they weren’t there,” she said.

Boat after boat came. Bus after bus left. “But they didn’t bring my children.”

Her phone died. She cried.

She was forced to head downtown.

For hours, she said she begged for information but relief workers had nothing to tell her about her children’s whereabouts. So she called the only other relative she has in Texas, her ex-husband.

Rescue workers had sent the children to Memorial Hermann hospital, and when they couldn’t reach their mother, they gave their father’s phone number.

Alghwaini’s kids are safe. But, for now, she’s alone, watching families all around her. “My car is flooded, everything is flooded. I can’t get to them,” she said. “It’s not easy.”