A motorist drives through heavy rain before the approaching Hurricane Harvey hits Corpus Christi, Texas on August 25, 2017 

CORPUS CHRISTI: Hurricane Harvey made landfall on the Gulf Coast of Texas late Friday, US meteorologists said, warning that "catastrophic flooding" was expected due to the heavy rains kicked up by the monster storm.

Harvey, which became a category 4 storm as it churned ashore, hit land at 10:00 pm (0300 GMT Saturday) near the town of Rockport, packing maximum sustained winds of 130 miles (215 kilometers) an hour, the National Hurricane Center said.

President Donald Trump heeded Texas Governor Greg Abbott´s call to declare a "disaster" zone in the state in order to speed federal aid to the millions of Americans in harm´s way both there and in Louisiana.

The arrival of the storm -- which was packing sustained winds of 130 miles (215 kilometers) an hour -- was the first major domestic challenge for Trump, who the White House said would head to the affected region early next week.

"We can obviously tell already at this stage this is going to be a very major disaster," a somber Abbott said, as more than 1,000 National Guardsmen were activated to help with evacuation and recovery.

"We´re going to be dealing with really record-setting flooding in multiple regions."

Hurricane-force winds started lashing the coast as night fell and coastal water levels rose.

Harvey, the first major storm of the annual Atlantic hurricane season, has forced hundreds of thousands to flee their homes, crippled oil production in the Gulf and wreaked havoc on air travel.

The National Hurricane Center (NHC) has warned of possible "catastrophic" flooding.

"All the advice we can give is get out, and get out now," said Patrick Rios, the mayor of Rockport, where a majority of the town´s 9,500 residents had left.

Rios had blunt words for those determined to stay, telling them to "mark their arm with a Sharpie pen, put their social security number" -- to be identified if found dead.

Before the storm hit, the US Federal Emergency Management Agency (FEMA) prepositioned emergency supplies and authorities issued mandatory evacuation orders in many areas.

As he headed to the Camp David presidential retreat for the weekend with his family, Trump said: "Good luck to everybody."

´Significant disaster´

Harvey is forecast to be the most powerful hurricane to hit the mainland since Wilma struck Florida in 2005, and could inflict billions of dollars in damage.

2005 was a huge year for hurricanes -- before Wilma, Hurricane Katrina pummelled New Orleans, leaving more than 1,800 dead and becoming one of the greatest hiccups in the presidency of George W. Bush.

Coast Guard Air Station Corpus Christi conducts a search and rescue mission for 12 people aboard a vessel taking on water prior to Hurricane Harvey near Port Mansfield, Texas, August 25, 2017

Coastal Texas is a fast-growing area, with some 1.5 million people moving into the area since 1999.

Authorities said the combination of dense growth and perhaps a year´s worth of rain falling in just days could prove deadly.

Local television footage showed supermarket aisles plucked bare, houses and shops with windows boarded over, and long lines snaking outside gas stations.

The NHC warned of the "complete destruction of mobile homes," of many buildings "washing away," and some areas being left "uninhabitable for weeks or months."

´Here to assist´

In 2005, Bush faced severe criticism after FEMA appeared unprepared for the devastating damage inflicted by Hurricane Katrina.

"Keep on top of hurricane Harvey don´t make same mistake Pres Bush made w Katrina," Republican Senator Chuck Grassley urged the US leader in a tweet.

In a series of tweets throughout Friday, Trump said he was closely monitoring the storm´s progress and said he was "here to assist as needed."

"Storm turned Hurricane is getting much bigger and more powerful than projected. Federal Government is on site and ready to respond. Be safe!" he said after arriving at Camp David.

Later on, he announced: "At the request of the Governor of Texas, I have signed the Disaster Proclamation, which unleashes the full force of government help!

Riding out the storm

In Corpus Christi, many residents appeared bent on sitting the storm out, packing sandbags to protect their homes -- until the supply of sandbags ran out.

Already, nearly 50,000 people in the city had lost power.

Sheriff Frank Osborne of Matagorda County, where evacuations were mandatory, described the high stakes.

People walk through wind driven rain together before the arrival of Hurricane Harvey on August 25, 2017 in Corpus Christi, Texas

"I´m not going to put one of my deputies´ life on the line to save somebody that didn´t leave when they were asked to," he told local TV station KHOU.

Officials in Houston, the biggest city in the storm´s path, closed its port but did not anticipate mass evacuations. Inland cities like San Antonio welcomed evacuees on Friday.

´Just terrifying´

FEMA chief Brock Long said the most pressing danger was the storm surge, but also said many inland counties should prepare for "significant" flooding.

One-third of the US refining capacity is potentially under threat. Crude prices rose slightly Friday ahead of landfall.

US authorities said about 22 percent of crude production in the Gulf of Mexico was shut down as of Friday mid-day -- or more than 375,000 barrels a day. But total daily US production stands at 9.5 million barrels a day, experts say.

In Louisiana, Governor John Bel Edwards issued an emergency declaration for his entire state, as authorities in New Orleans -- where Katrina did the most damage -- readied high-water rescue vehicles and boats.

Edwards described a "worse-case scenario" in which the storm leaves Texas, gains new strength over the heated waters of the Gulf, and then heads toward Louisiana.

Meteorologist Eric Holthaus told AFP the prospect of the storm stalling on the coast, lashing it with heavy rain for days, was "just terrifying."