Authorities in Dallas are turning the city’s main convention center into a “mega-shelter” to accommodate the thousands of Texans forced to evacuate their homes amid Hurricane Harvey’s “unprecedented” flooding. The shelter will reportedly be able to host as many as 5,000 evacuees, with county officials, charity groups, and local hospitals aiming to have the center open by Tuesday morning, CNN reports. With the Coast Guard performing hundreds of aerial rescues and National Guard soldiers pulling trapped residents out of submerged homes, authorities in Houston have called on volunteers with boats to assist in rescue efforts. More than 1,000 people were rescued in one night alone, Houston Mayor Sylvester Turner said. As of Sunday night, 54 of the state’s 254 counties were declared disaster zones, with as much as 10 more inches of rain expected by Monday morning.