HORSESHOE BEACH, Fla. (AP) — Tropical Storm Debby slammed Florida with catastrophic flooding and was blamed for at least four deaths, with Georgia and South Carolina next in line as the system rips across the southeastern United States.

Record-setting rain was forecast to cause flash flooding in coastal Georgia and South Carolina, and into North Carolina, with up to 30 inches of rainfall in some areas. Debby made landfall early Monday as a Category 1 hurricane over the gulf coast of Florida.

The tropical storm was moving slowly, covering roads with water and contributing to at least four deaths.

A truck driver died on Interstate 75 in the Tampa area after he lost control of his tractor trailer, which flipped over a concrete wall and dangled over the edge before the cab dropped into the water below. Sheriff’s office divers located the driver, a 64-year-old man from Mississippi, in the cab 40 feet below the surface, according to the Florida Highway Patrol.

A 13-year-old boy died Monday morning after a tree fell on a mobile home located southwest of Gainesville, according to the Levy County Sheriff’s Office.

And in Dixie County, just east of where the storm made landfall, a 38-year-old woman and a 12-year-old boy died in a car crash on wet roads Sunday night. The Florida Highway Patrol said a 14-year-old boy who was a passenger was hospitalized with serious injuries.

Hundreds of thousands of customers remained without power in Florida and Georgia on Monday afternoon, down from a peak of more than 350,000, according to PowerOutage.us and Georgia Electric Membership Corp.

Florida Gov. Ron DeSantis said some 17,000 linemen were working to restore electricity. He warned residents in affected areas to sit tight until conditions are safe.

“When the water rises, when you have streets that can be flooded, that’s hazardous,” DeSantis said. “Don’t try to drive through this. We don’t want to see traffic fatalities adding up.”

Airports were also affected. More than 1,600 flights had been canceled nationwide, many of them to and from Florida airports, according to FlightAware.com. One out of every five flights scheduled to leave Orlando International Airport was canceled Monday. Nearly 30% of flights scheduled to depart Tampa International Airport were canceled.

Sarasota, a beach city popular with tourists, was one of the hardest hit by flooding.

“Essentially we’ve had twice the amount of the rain that was predicted for us to have,” said Sarasota County Fire Chief David Rathbun in a social media update.

The storm made landfall early Monday morning near Steinhatchee, a tiny community in northern Florida of less than 1,000 residents.

Taylor County, where Steinhatchee is located, closed several roads due to flooding, Sheriff Wayne Padgett said. Trees and power lines had also fallen across some roads. Padgett advised anyone who had evacuated from low-lying or coastal areas to wait before returning to their homes because the tide had not come in, and it was unclear how deep floodwaters might get later.

Looking out over the Steinhatchee River from the condo above the marina he operates, Chris Williams said he was feeling blessed that the damage wasn’t worse. Williams said his power went out at about 5:30 a.m. Monday as the storm was washing ashore, jamming the dock-studded riverfront with tree debris and barrels.

The small community is roughly 20 miles (32 kilometers) from where Hurricane Idalia crashed ashore less than a year ago.

“Two in less than a year is pretty bad,” Williams said. “You do everything you can possibly do to prepare. And when you’ve done that, clean up and put it back together and move forward.”

President Joe Biden was briefed on Debby’s progress while at his home in Wilmington, Del., the White House said.

Vice President Kamala Harris has postponed a scheduled trip to Georgia amid the ongoing effects of Tropical Storm Debby. Harris’ campaign said her stop planned in Savannah, Ga., on Thursday, was being put off due to the storm.