Hurricane Harvey has slowed over southeast Texas early Saturday as a Category 1 storm with 90-mph winds, reports say, leaving a path of disaster from it's touchdown Friday night. 

While the hurricane downgraded from a Category 4, the National Weather Service warns it's only the beginning of major flooding, with up to 3-feet of rain expected in some areas. (For comparison, Hurricane Katrina was a Category 3 storm when it made landfall in Louisiana in 2005 and Hurricane Ike, which made landfall in Galveston in 2008, was a Category 2.) A flash flood watch remains in effect across southern Texas until Tuesday evening, as Harvey is expected to stall and spin for the next three to five days.

Harvey "may be nothing short of a flooding disaster," for Texas, according to AccuWeather meteorologist Alex Sosnowski, who said some communities could be underwater for days. Forecasters were already measuring 28-foot-high waves near the eye of the storm.

Cities are assessing hurricane damage, and there have been some reports of injuries. 

According to The Associated Press, Rockport, a coastal city of about 10,000 people, was directly hit when Harvey came ashore.

Rockport City Manager Kevin Carruth told KIII-TV that multiple people were taken to the county’s jail for assessment and treatment after the roof of a senior housing complex collapsed. Carruth also said that the historic downtown area has also sustained heavy damage, according to KIII-TV.

As of late Friday night, at least 10 people were treated for injuries, KIII-TV reported.

Corpus Christi police said a homeowner shot an intruder after Hurricane Harvey made landfall. The victim was "coherent" when he was rushed to a hospital, police say.

As of early Saturday morning, the Electric Reliability Council of Texas said in a statement that more than 211,000 consumers were without power along the Gulf Coast, with more than 100 circuits currently out of service

Harvey is the first major hurricane — classified as Category 3 or above — to hit the U.S. since Hurricane Wilma in 2005. Harvey gradually weakened after hitting the coastal cities, with the National Hurricane Center downgrading it to a Category 2 storm though it still sustained 110-mph winds.

More: Hurricane Harvey smacks Texas: What we know now

More: Here's how to help victims of Hurricane Harvey

Late Friday, federal authorities granted Texas Gov. Greg Abbott's State of Disaster request for 700 National Guard members in 30 counties to help with emergency disaster relief associated with the expected damage from Harvey.

He warned of record-setting flooding in multiple regions of the state and urged people to get out of harm's way. “You don’t want to put yourself in a situation where you could be subject to a search and rescue.”

Kirsten Crow, Rick Jervis, Doug Stanglin and Doyle Rice of the USA TODAY NETWORK contributed to this report.