PORT ARTHUR, Texas/HOUSTON (Reuters) – A week after Hurricane Harvey came ashore in Texas, rescuers pressed their marathon search for survivors on Friday in large pockets of land that remained flooded by one of the costliest natural disasters to hit the United States.

The storm has displaced more than 1 million people with 44 feared dead from flooding that paralyzed Houston, swelled river levels to record highs and knocked out the drinking water supply in Beaumont, Texas, a city of about 120,000 people.

Chemicals maker Arkema SA and public health officials warned of the risk of more explosions and fires at a plant owned by the company. Blasts had rocked the facility, about 25 miles east of Houston and zoned off inside a 1.5-mile (2.4-km) exclusion zone, on Thursday after it was engulfed by floodwater.

With three months to go in the official Atlantic hurricane system, a new storm, Irma, had strengthened into a Category 3 storm, the midpoint of the five-step Saffir-Simpson scale, on Friday. It remained hundreds of miles from land but was forecast to possibly hit the U.S. territory of Puerto Rico, the Dominican Republic and neighboring Haiti by the middle of next week.

Harvey shut about a quarter of U.S. refinery capacity, much of which is clustered along the Gulf Coast, and caused gasoline prices to spike to a two-year high ahead of the long Labor Day holiday weekend.

With the presence of water-borne contaminants a growing concern, the National Weather Service issued flood watches from Arkansas into Ohio on Friday as the remnants of the storm made their way through the U.S. heartland.

The Neches River, which flows into Beaumont and nearby Port Arthur, was forecast for a record crest from Friday well above flood levels.

Two of the last people remaining in their flooded home near the river, Kent Kirk, 58, and Hersey Kirk, 59, were pulled to safety late Thursday.

“They were the last holdouts, the last house,” said Dennis Landy, a neighbor who had spent the day in his ferrying people by boat from a small, remote group of houses near Rose City, Texas, close to the Neches’ banks, to safety.

It took an hour of coaxing by a rescuer but Hersey Kirk finally let herself be carried from her wheelchair to the boat and then to a Utah Air National Guard helicopter.

“I‘m losing everything again,” she said. “We got flooded in Ike, in Rita. My husband just got a new car – well it was new to him anyway. It’s sitting in 5 feet of water.”

Harvey roared ashore a week ago as the most powerful hurricane to hit Texas in half a century. It dumped unprecedented amounts of rain and left devastation across more than 300 miles (482 km) in the southeast of the state.

GASOLINE PRICES SPIKE

The national average for a regular gallon of gasoline has risen 17 cents since the storm hit, hitting $2.519 as of Friday morning, the highest since August 2015, according to motorists group AAA. Oil prices have slipped over the week in response. [O/R]

Several East Coast refineries have run out of gasoline to deliver, raising fears that travelers will face fuel shortages during the three-day holiday.

In major Texas cities including Dallas, there were long lines at gas stations, prompting state regulators to tell people they were sparking a panic and saying there were ample fuel supplies.

The storm came on the 12th anniversary of Hurricane Katrina, which killed about 1,800 around New Orleans. Then-U.S. President George W. Bush’s administration was roundly criticized for its botched early response to the storm.

Signaling that he did not want to be seen as repeating those mistakes, President Donald Trump plans a second visit to the storm-hit region on Saturday.

“Texas is healing fast thanks to all of the great men & women who have been working so hard. But still so much to do. Will be back tomorrow!” Trump said on Twitter on Friday.

Moody’s Analytics estimated the economic cost from Harvey for southeastern Texas at $51 billion to $75 billion, ranking it among the costliest storms in U.S. history. Much of the damage has been to Houston, the U.S. energy hub.

At least 44 people were dead or feared dead in six counties including and around Houston, officials said. Another 19 remained missing.

Some 779,000 Texans have been told to leave their homes and another 980,000 fled voluntarily amid dangers of new flooding from swollen rivers and reservoirs, according to federal estimates.

Tens of thousands crowded in evacuation centers across the region.

As signs of normal life returned to Houston, the nation’s fourth most populous city, there were concerns about health risks from bacteria and pollutants in floodwater.

For a graphic on Harvey’s energy impact, click: here