With its flood defenses strained, the crippled city of Houston anxiously watched dams and levees Tuesday to see if they would hold until the rain stops, and meteorologists offered the first reason for hope — a forecast with less than an inch of rain and even a chance for sunshine.

The human toll continued to mount, both in deaths and in the ever-swelling number of scared people made homeless by the catastrophic storm that is now the heaviest tropical downpour in U.S. history.

The death toll from Harvey has risen to at least 18 as three more fatalities have been confirmed in the Houston area.

The Harris County Institute of Forensic Sciences updated its storm-related deaths Tuesday night to include an 89-year-old woman, Agnes Stanley, who was found floating in 4 feet (1.2 meters) of floodwater in a home. A 76-year-old woman was found floating in floodwater near a vehicle. Her name was not released. A 45-year-old man, Travis Lynn Callihan, left his vehicle and fell into floodwaters. He was taken to a hospital, where he died Monday.

Family members and authorities have reported at least 18 deaths although the bodies of some victims apparently swept away in the floodwaters have not been found.

The city’s largest shelter was overflowing when the mayor announced plans to create space for thousands of extra people by opening two and possibly three more mega-shelters.

“We are not turning anyone away. But it does mean we need to expand our capabilities and our capacity,” Mayor Sylvester Turner said. “Relief is coming.”

The rescues went on. Federal and local agencies said they had lifted more than 13,000 people out of the floodwaters in the Houston area and surrounding cities and counties.

Louisiana’s governor offered to take in Harvey victims from Texas, and televangelist Joel Osteen opened his Houston megachurch, a 16,000-seat former arena, after critics blasted him on social media for not acting to help families displaced by the storm.

Meteorologists said the sprawling city would soon get a chance to dry out.

When Harvey returns to land Wednesday, “it’s the end of the beginning,” National Hurricane Center meteorologist Dennis Feltgen said.

Harvey will spend much of Wednesday dropping rain on Louisiana before moving on to Arkansas, Tennessee and parts of Missouri, which could also see flooding.

But Feltgen cautioned: “We’re not done with this. There’s still an awful lot of real estate and a lot of people who are going to feel the impacts of the storm.”

The National Weather Service predicted less of an inch of rain for Houston on Wednesday and only a 30 percent chance of showers and thunderstorms for Thursday. Friday’s forecast called for mostly sunny skies with a high near 94.

In all, more than 17,000 people have sought refuge in Texas shelters, and that number seemed certain to increase, the American Red Cross said.

The city’s largest shelter, the George R. Brown Convention Center, held more than 9,000 people, almost twice the number officials originally planned to house there. The crowds included many from outside Houston.

By the end of the day, the Toyota Center, home of the NBA’s Rockets, had begun accepting people who could not find space at the convention center.

Louisiana Gov. John Bel Edwards said he expected Texas officials to decide within 48 hours whether to accept his offer, which comes as Louisiana deals with its own flooding. About 500 people were evacuated from flooded neighborhoods in southwest Louisiana, Edwards said.

The city has asked the Federal Emergency Management Agency for more supplies, including cots and food, for an additional 10,000 people, said the mayor, who hoped to get the supplies no later than Wednesday.

In an apparent response to scattered reports of looting, the mayor also imposed a curfew. Police Chief Art Acevedo said violators would be questioned, searched and arrested.

Four days after the storm ravaged the Texas coastline as a hurricane, authorities and family members have reported more than a dozen deaths from Harvey. They include a woman killed when heavy rain sent a large oak tree crashing onto her trailer and another woman who apparently drowned after her vehicle was swept off a bridge.

Houston police confirmed that a 60-year-old officer drowned in his patrol car after he became trapped in high water while driving to work. Sgt. Steve Perez had been with the force for 34 years.

Six members of a family were feared dead after their van sank into Greens Bayou in East Houston. A Houston hotel said one of its employees disappeared while helping about 100 guests and workers evacuate the building.

Authorities acknowledge that fatalities from Harvey could soar once the floodwaters start to recede from one of America’s largest metropolitan centers.

A pair of 70-year-old reservoir dams that protect downtown Houston and a levee in a suburban subdivision began overflowing Tuesday, adding to the rising floodwaters.

Engineers began releasing water from the Addicks and Barker reservoirs Monday to ease the strain on the dams. But the releases were not enough to relieve the pressure after the relentless downpours, Army Corps of Engineers officials said. Both reservoirs are at record highs.

The release of the water means that more homes and streets will flood, and some homes will be inundated for up to a month, said Jeff Linder of the Harris County Flood Control District.

Brazoria County authorities posted a message on Twitter warning that the levee at Columbia Lakes south of Houston had been breached and telling people to “GET OUT NOW!!” Brazoria County Judge Matt Sebesta said residents were warned that the levee would be overtopped at some point, and a mandatory evacuation order was given Sunday.

The levee was later fortified, but officials said they did not know how long the work would hold.

Officials in Houston were also keeping an eye on infrastructure such as bridges, roads and pipelines that are in the path of the floodwaters.

Water in the Houston Ship Channel, one of the nation’s busiest waterways, which serves the Port of Houston and Houston’s petrochemical complex, is at levels never seen before, Linder said.

The San Jacinto River, which empties into the channel, has pipelines and roads and bridges not designed for the current deluge, Linder said, and the chance of infrastructure failures will increase the “longer we keep the water in place.”

Among the worries is debris coming down the river and crashing into structures and the possibility that pipelines in the riverbed will be scoured by swift currents. In 1994, a pipeline ruptured on the river near Interstate 10 and caught fire.

During a visit to the storm zone, President Donald Trump kept his distance from the epicenter of the damage in Houston to avoid disrupting recovery operations. But he planned to return to the region Saturday to meet with some of the victims, press secretary Sarah Huckabee Sanders said.

After five consecutive days of rain, Harvey set a new continental U.S. record for rainfall for a tropical system.

The rains in Cedar Bayou, near Mont Belvieu, Texas, totaled 51.88 inches (1.32 meters) as of Tuesday afternoon. That’s a record for both Texas and the continental United States, but it does not quite surpass the 52 inches (1.33 meters) from Tropical Cyclone Hiki in Kauai, Hawaii, in 1950, before Hawaii became a state.

The previous record was 48 inches (1.22 meters) set in 1978 in Medina, Texas, by Tropical Storm Amelia. A weather station southeast of Houston reported 49.32 inches (1.25 meters) of rain.

Before it breaks up, Harvey could creep as far east as Mississippi by Thursday, meaning New Orleans, where Hurricane Katrina unleashed its full wrath in 2005, is in Harvey’s path. Foreboding images of Harvey lit up weather radar screens on the 12th anniversary of the day Katrina made landfall in Plaquemines Parish.

The disaster is unfolding on an epic scale, with the nation’s fourth-largest city mostly paralyzed by the storm that arrived as a Category 4 hurricane and then parked over the Gulf Coast. The Houston metro area covers about 10,000 square miles (25,900 square kilometers), an area slightly bigger than New Jersey.

(AP)