(CNN) Days after Harvey struck, Houston Mayor Sylvester Turner struck an optimistic tone on Thursday, declaring the city "is open for business." The mayor and other officials pointed to small signs of recovery, such as fewer people in shelters, more bus lines resuming and the city's shipping channel reopening on a limited basis.

The mayor said parts of Houston still face flooding issues because of standing water but the rest of the city is drying out. Traffic is returning to the roadways and power has been restored to much of the region. And the Houston Astros will play a doubleheader at home on Saturday, Turner said.

"We are turning the corner," he said.

Turner added: "The city of Houston is open for business. And quite frankly, we're open for business right now."

But flood-stricken southeast Texas was still struggling with a new series of blows that left one city without running water, the operators of a flood-damaged chemical plant warning of additional fires and at least one hospital unable to care for patients.

Nearly a week after Hurricane Harvey slammed into the Texas coast, desperate residents remain stranded without food and water in the wake of unprecedented flooding. Meanwhile, authorities continue searching for survivors and made helicopter rescues from rooftops as the death toll from Harvey climbed to at least 47.

Given the disaster's scope, the commanding officer who led the federal response to Hurricane Katrina a dozen years ago questioned the adequacy of current relief efforts.

"When you have a combination of hurricane winds, flooding now for five days and you start losing the water and the electric grid, this is a game changer," retired Lt. Gen. Russel Honoré told CNN on Thursday.

"Losing electricity itself is a disaster for over a 24-hour period in America to any person because we lose access to water, we lose access to sewers, we lose our ability to communicate."

Janice Forse cries at a shelter Wednesday in Beaumont after her home was flooded.

The dangers emerging from the historic storm seem to increase by the day.

Beaumont, east of Houston, has no running water after both its water pumps failed, forcing a hospital to shut down. City officials could not say when service would be restored.

In Crosby, two blasts rocked a flooded chemical plant, and more could come.

And in Houston, authorities started going door to door looking for victims, hoping to find survivors but realizing that the death toll could rise.

Rainfall totals would fill Houston Astrodome 85,000 times

The storm dumped an estimated 27 trillion gallons of rain over Texas and Louisiana over six days, said Ryan Maue, of the weather analytics company WeatherBell. That's enough to fill the Houston Astrodome 85,000 times or San Francisco Bay 10.6 times at high tide.

"We will see additional losses of life, if history is any precedent here," Tom Bossert, homeland security adviser to President Donald Trump, told reporters Thursday.

The storm has damaged or destroyed about 100,000 homes, Bossert said.

Trump plans to donate $1 million of his money to help storm victims, according to the White House.

"You should continue to have confidence in what we're doing as a government," Bossert said. "But I would be remiss if I didn't stop and say that none of that matters if you're an affected individual."

FEMA reported Thursday that more than 96,000 people in Texas have been approved for emergency assistance, including financial aid for rent and lost property. More than $57 million has already been distributed for housing, personal property and transportation assistance.

In the hard-hit city of Rockport, Vice President Mike Pence on Thursday addressed residents outside a church.

"President Trump sent us here to say, 'We are with you. The American people are with you,'" said Pence, who later announced that Trump will visit Houston and other areas on Saturday.

Company warns of more blasts

A pair of blasts at the Arkema chemical plant in Crosby sent plumes of smoke into the sky Thursday morning, and the company warned more blasts could follow.

"We want local residents to be aware that product is stored in multiple locations on the site, and a threat of additional explosion remains," Arkema said . "Please do not return to the area within the evacuation zone until local emergency response authorities announce it is safe to do so."

Overheated organic peroxides caused blasts at a chemical plant in Crosby.

The twin blasts Thursday morning happened after organic peroxide overheated. The chemicals need to be kept cool, but the temperature rose after the plant lost power, officials said.

Containers popped. One caught fire and sent black smoke 30 to 40 feet into the air.

The thick smoke "might be irritating to the eyes, skin and lungs," Arkema officials said.

Fifteen Harris County sheriff's deputies were hospitalized, but the smoke they inhaled was not believed to be toxic, the department said. The deputies have all been released.

Harris County Sheriff Ed Gonzalez said nothing toxic was emitted and there was no imminent danger to the community.

Three other containers storing the same chemical are at risk of "overpressurization," said Jeff Carr of Griffin Communications Group, which is representing Arkema.

Arkema shut down the facility as Harvey approached last week. The company evacuated everyone within 1.5 miles of the plant as a precaution after it was flooded under more than 5 feet of water.

The company has said there's a small possibility the organic peroxide, which is used in the production of plastic resins, could seep into floodwaters, without igniting or burning.

Harvey forced the shutdown of many chemical or oil plants, including the Colonial Pipeline , which carries huge amounts of gasoline and other fuel between Houston and the East Coast. Valero and Motiva, the largest refinery in the country , have also closed some facilities.

'People are freaking out' in Beaumont

Extreme flooding caused both of Beaumont's water pumps to fail, leaving about 135,000 people without water on Thursday, said Jefferson County Judge Jeff Branick.

"We will have to wait until the water levels from this historical flood recede before we can determine the extent of damage and make any needed repairs," the city said. "There is no way to determine how long this will take at this time."

City officials plan to establish a water distribution point on Friday.

Meanwhile, earlier Thursday, residents lined up at stores hours before they opened in hopes of getting whatever bottled water they could find.

Standing in line in Beaumont Tx at Market Basket to buy #water. It's 7am, they open at 9. pic.twitter.com/cFqpxT67Rr — Maggi Carter (@maggicarter) August 31, 2017

"It's crazy," said Khayvin Williams, who started waiting in line at Market Basket at 6:50 a.m. "People are freaking out."

At a local Walmart, Jeffrey Farley said the store was only allowing 20 people in at a time and was rationing water to three cases per customer. He got in line at 6:30 a.m. and waited until 8:30 to get his water.

"It's an insult to injury for a lot of folks," Farley said. "The water situation has made things dire for everyone here."

Beaumont, along with Port Arthur, was devastated after Harvey made another landfall Wednesday.

The failure of the city's water pump forced the closure of Beaumont-based Baptist Hospitals of Southeast Texas

"Due to the citywide lack of services, we have no other alternative but to discontinue all services, which will include emergency services," the hospital system said Thursday.

Patients in stretchers and wheelchairs were evacuated to other hospitals by ambulance and helicopter.

"We had no idea when we went to bed at midnight that ... we'd get the call that says the hospital would need to think about the city's water being lost," hospital spokeswoman Mary Poole said. "We did not expect that and that's a game changer for us."

About 20 miles southeast of Beaumont, in Port Arthur, those lucky enough to get to a shelter were deluged again, when murky brown floodwater filled an evacuation shelter

Evacuees at a Port Arthur emergency shelter battle flooding once more after leaving their homes.

Actress Amber Chardae Robinson, speaking by phone from Beaumont, said getting out of Port Arthur was virtually impossible.

"Every avenue we use to get out of the city is flooded -- to get to Houston is flooded, to get to Louisiana is flooded," she said. "So people are just trying to figure out ways to get their family out of there at this point."

In most of Orange County, east of Beaumont, a mandatory evacuation order was issued Thursday afternoon by Judge Stephen Brint Carlton. The order primarily involved areas along the Neches and Sabine rivers.

Death toll expected to rise

Across the state, families are searching tirelessly for missing relatives six days after Harvey first pummeled the Texas coast

Photos: Hurricane Harvey slams Texas Photos: Hurricane Harvey slams Texas Downtown Houston is seen behind the flooded Buffalo Bayou a few days after Hurricane Harvey came ashore in August 2017. The Category 4 storm caused historic flooding. It set a record for the most rainfall from a tropical cyclone in the continental United States, with 51 inches of rain recorded in areas of Texas. An estimated 27 trillion gallons of water fell over Texas and Louisiana during a six-day period. Hide Caption 1 of 22 Photos: Hurricane Harvey slams Texas NASA astronaut Jack Fischer photographed Hurricane Harvey from the International Space Station. Hide Caption 2 of 22 Photos: Hurricane Harvey slams Texas Steve Culver comforts his dog Otis in the hurricane aftermath. Harvey destroyed most of his home in Rockport while he and his wife were there. Hide Caption 3 of 22 Photos: Hurricane Harvey slams Texas Houston police officer Daryl Hudeck carries Catherine Pham and her 13-month-old son, Aiden, after rescuing them from floodwaters. Hide Caption 4 of 22 Photos: Hurricane Harvey slams Texas A damaged home is seen in the Key Allegro neighborhood of Rockport. Hide Caption 5 of 22 Photos: Hurricane Harvey slams Texas A car is submerged by floodwaters on a freeway near downtown Houston. Hide Caption 6 of 22 Photos: Hurricane Harvey slams Texas Melani Zurawski cries while inspecting her home in Port Aransas, Texas. Hide Caption 7 of 22 Photos: Hurricane Harvey slams Texas A graveyard is flooded in Pearland, Texas. Hide Caption 8 of 22 Photos: Hurricane Harvey slams Texas Soldiers with the National Guard patrol Rockport, looking for residents trapped in their homes. Hide Caption 9 of 22 Photos: Hurricane Harvey slams Texas Evacuees are loaded onto a truck in Houston. Hide Caption 10 of 22 Photos: Hurricane Harvey slams Texas People push a stalled pickup through a flooded street in Houston. Hide Caption 11 of 22 Photos: Hurricane Harvey slams Texas Rockport residents return to their destroyed home. Hide Caption 12 of 22 Photos: Hurricane Harvey slams Texas Rescue boats fill Tidwell Road in Houston as they help flood victims evacuate the area. Hide Caption 13 of 22 Photos: Hurricane Harvey slams Texas People wait to be rescued from their flooded home in Houston. Hide Caption 14 of 22 Photos: Hurricane Harvey slams Texas Volunteers in Dallas organize items donated for hurricane victims. Hide Caption 15 of 22 Photos: Hurricane Harvey slams Texas When Harvey slammed the Texas coast and flooded much of Houston, volunteers sprang into action. Some came from as far away as the Florida Everglades, boats in tow, ready to rescue people trapped in their homes. Hide Caption 16 of 22 Photos: Hurricane Harvey slams Texas Larry Koser Jr. and his son Matthew look for important papers and heirlooms inside a flooded home in Houston. Hide Caption 17 of 22 Photos: Hurricane Harvey slams Texas Members of the National Guard rest at a furniture store in Richmond, Texas. Hide Caption 18 of 22 Photos: Hurricane Harvey slams Texas Volunteer rescue workers help a woman from her flooded home in Port Arthur, Texas. Hide Caption 19 of 22 Photos: Hurricane Harvey slams Texas This aerial photo shows flooded residential neighborhoods in Houston. Hide Caption 20 of 22 Photos: Hurricane Harvey slams Texas Tammy Dominguez and her husband, Christopher, sleep on cots at the George R. Brown Convention Center, where thousands of people were taking shelter in Houston. Hide Caption 21 of 22 Photos: Hurricane Harvey slams Texas An elderly patient waits to be rescued from the Gulf Health Care Center in Port Arthur. The facility was evacuated with the help of first responders and volunteers. Hide Caption 22 of 22

More than 72,000 people have been rescued so far, according to officials.

Among the storm-related deaths are a Houston man who was electrocuted while walking in floodwaters and a mother whose body was floating about a half mile from her car. Rescuers found her daughter clinging to her body. The child is in stable condition after suffering from hypothermia.

"We just pray that the body count ... won't rise significantly," Houston Police Chief Art Acevedo said Wednesday.

But Houston received a bit of good news Thursday. The pool level at Barker Reservoir -- which officials feared would overflow -- has peaked and is going down, the Army Corps of Engineers said.

Residents evacuate their homes near Houston's Addicks Reservoir on Tuesday.

And the city's Addicks Reservoir, which was overwhelmed and caused widespread flooding this week, has also peaked. The water in that reservoir is also receding.

In a light moment amid the destruction, Houston police posted a video Thursday of an officer's daughter serenading him on his birthday.

When #HurricaneHarvey keeps you from home on your birthday, you're serenaded over the phone by your daughter #HoustonStrong pic.twitter.com/ldHDHeBaaI — Houston Police (@houstonpolice) August 31, 2017

But in Victoria, about 120 miles southwest of Houston, Mary Martinez returned to her heavily damaged home Wednesday.

"I did not think it was going to be this bad," said Martinez, who received assistance from volunteers with Christian charity Samaritan's Purse. "I was speechless."

Man tried to warn off friend from electrical wire

Countless stories of heroism have emerged in the aftermath of Harvey, including by some of the victims.

Andrew Pasek was walking through 4 feet of water trying to get to his sister's house when he accidentally stepped on a live electrical wire.

"He felt the charge and knew something was wrong right away and tried to shake it off right away," said his mother, Jodell.

The 25-year-old quickly asked a friend to get away from him "because if you do, you know, you will go, too," he told his friend.

Pasek was electrocuted. His mother said no one could try to resuscitate him for an hour, until the electricity was turned off.

"It could have been anybody," she said.