To back up his plea, McMaster cited a video of law enforcement officers on Edisto Beach rescuing a vehicle stuck in the storm's surge.
"Samaritan's Purse will first respond to the island of St. Maarten, where Irma ripped apart buildings and claimed multiple lives", the group said in an update.
That crucial flood-protection infrastructure is still being rebuilt in some places, which means flooding could still be a problem even if Irma brings less storm surge than Matthew. "We all sort of scattered around the country when we evacuated, so we're trying to stay in touch", said Suzanne Trottier, who left her Key West, Florida, home for Virginia nearly a week ago ahead of Irma.
That decision would be made with local law enforcement and emergency management agencies, McMaster said.
Officials said the storm has caused flooding in downtown Charleston and they have closed a bridge due to high winds.
On Thursday, President Trump approved South Carolina's emergency disaster declaration so it can get ready for the storm's impact.
McMaster said he is also concerned that when the rain stops and winds die down, people will immediately want to get out of the house and explore damage and could be injured. "There's so many variables associated with where the storm can go", Bryson said, urging people not to become complacent.More news: Executive: Samsung Elec's Galaxy Note 8 pre-orders highest among Note series
The National Weather Service declared a flash food emergency for downtown Charleston on Monday afternoon as heavy rain moved inland after a storm surge-fueled high tide swamped the city's downtown. "Travel is not advised".
Nearby states also began to feel the wallop of Irma on Monday. N.C. Department of Transportation crews in every county are reviewing stock of drainage pipes. Irma, the most powerful storm ever recorded in the Atlantic, remained a Category 5 storm with winds of 175 miles per hour as of 5 p.m., according to the U.S. National Hurricane Center. It poured across Lockwood Boulevard by the City Marina; it filled the low-lying areas around the Medical University of SC and washed over the road by the Washout on Folly Beach. "Whether there's more folks on the road or more staying home, that will be an indicator". However, if residents must drive, they were warned not to drive around barricades.
The governor has issued an executive order directing all 2,370 public and private dam owners to look at their water levels and go ahead and lower them safely because of the anticipated rise in water levels.
The shelter in North Charleston is available to residents and their pets.
Georgia reported more than 570,000 homes and businesses without electricity, and there were 80,000 in SC. The state's emergency management officials said the storm cut power to more than 6.5 million account holders across the state as of Monday afternoon.
But the focus remains on the Lowcountry and barrier islands at this time where the governor issued an evacuation order over the weekend.
"Let me make it perfectly clear, we have absolutely no tolerance for anyone who would try to take advantage of this storm", McMaster assures.