HOUSTON (AP/KDKA) – Crews overwhelmed by thousands of rescue calls during one of the heaviest downpours in U.S. history have had little time to search for other potential victims. But officials acknowledge the grim reality that fatalities linked to Harvey could soar once the devastating floodwaters recede.

Even worse, officials now worry that the worst may be yet to come.

CBS News has confirmed at least three deaths linked to Harvey. Two are from the Houston area, including a 60-year-old woman who was killed when a tree fell on her home as she slept. The third confirmed victim died in a fire near Corpus Christi.

More than three days after the storm ravaged the Texas coastline as a Category 4 hurricane, authorities worry that the tropical storm now parked over the Gulf Coast will return and deliver a knock-out blow to a Houston region already ravaged by devastating downpours generating an amount of rain normally seen only once in more than 1,000 years.

Some fear that may be more than the nation’s fourth-largest city could bear.

The second night inside the George R. Brown Convention Center was louder, more crowded and at times, more chaotic.

People who escaped rising floodwaters and pouring rain arrived at the shelter Monday night by the busload and truckload even as the convention center exceeded its capacity of 5,000.

Volunteers pushed cots together to make space on the floor for the roughly 7,000 people. The demand on the convention center was expected to grow with more rain forecast Tuesday.

David Brady, CEO of the Red Cross’ Texas Gulf Coast chapter, says creating a friendly, open and welcoming culture is key.

But for Kevin Perkins, displaced by the storm, the experience was different. He described sleeping on the floor and feeling accosted by police officers inside: “It’s hell.”

Harvey is threatening to also inundate southwestern Louisiana with potentially disastrous flooding.

Emergency personnel continued to rescue people from flooding homes early Tuesday morning in Lake Charles, as rainfall after sunset Monday sent water into homes in neighborhoods unaccustomed to flooding.

Flash flood warnings and watches were in effect for much of the region overnight and forecasters said 10 inches (25 centimeters) or more rain could fall this week.

Few homes flooded earlier Monday, but a heavy band of rain on the east side of Lake Charles tipped the scales for some neighborhoods.

Although Louisiana doesn’t appear to be facing a threat equal to Harvey’s catastrophic toll in Texas, images of devastation revived painful memories for survivors of Hurricane Katrina, which made landfall in Louisiana on Aug. 29, 2005.