Two people were killed as subtropical storm Alberto's strong surf, powerful wind gusts and heavy rains tore across the Gulf of Mexico coast and swamped the Southeast, officials and forecasters said Monday.

Alberto, the first named storm of the hurricane season, made landfall on Florida's Panhandle on Monday afternoon, washing out the unofficial start of summer.

In Polk County, North Carolina, two television journalists were killed when a tree fell on their vehicle, state Trooper Rico Stephens said. Their station, NBC affiliate WYFF of Greenville, South Carolina, identified them as anchor Mike McCormick and photographer Aaron Smeltzer.

"All of us at WYFF News 4 are grieving," the station said in a tweet. "We are a family."

Tryon Fire Chief Geoff Tennant added that he'd done an interview with McCormick shortly before his death.

"We had talked a little bit about how he wanted us to stay safe and how we wanted him to stay safe," Tyron told reporters. "Of course, 10, 15 minutes later we get the call and it was him and his photographer."

Polk County warned in a Facebook post that the area where the incident occurred — just north of the South Carolina state line — had become dangerous and more flash flooding was possible through Wednesday.

Alberto was maintaining its strength and was centered about 15 miles west-northwest of Panama City, Florida, according to a 5 p.m. ET update from the National Hurricane Center, or NHC,in Miami. The storm had maximum sustained winds of 45 mph, having weakened slightly since the morning.

Forecasters warned of life-threatening surf conditions and the possibility of a few brief tornadoes in much of Florida and parts of Georgia, South Carolina and Alabama. It said heavy rains were also expected, giving coastal residents a taste of what forecasters recently predicted would be an active hurricane season.

"Given the short period of time before Alberto makes landfall, its overall ragged appearance and proximity to dry air, little change in strength is expected before the subtropical storm reaches the coast," said John Cangialosi, a hurricane specialist at the NHC.

In Cuba, where Alberto's outer bands dumped about a foot of rain overnight — causing rivers and reservoirs to overflow — the storm shut down railroad service, an oil refinery and parts of the country's national highway, according to state television and Cuba's National Meteorological Institute.

About 20,000 people were evacuated across the island.

Alberto comes at the same time as a separate storm system that raked the mid-Atlantic over the weekend and deluged the community of Ellicott City, Maryland, which was swamped by a river that rose by 17 feet in just two hours.

Across the Gulf Coast, residents were bracing for their own misery. Lifeguards posted red flags along the white sands of Pensacola Beach, Florida, where swimming and wading were banned amid high surf and dangerous conditions.

Panama City resident Jo Newton said she was filling up sandbags "to hopefully keep the water from coming in my front door."

"I'm actually terrified of the amount of rain that is predicted to come in," she said.

Slow-moving Alberto could drop 4 to 8 inches of rain from the Florida Panhandle into parts of Alabama and western Georgia as it hangs around the region into midweek, forecasters said. The Tennessee Valley and the Carolinas could get soaked with 2 to 6 inches into Wednesday morning.

Recent heavy rains in the Southeast could also make flooding worse in some areas of Florida and through the Carolinas where the ground is saturated, according to the National Weather Service.

The storm's approach triggered mandatory evacuations of some small, sparsely populated Gulf Coast barrier islands in Florida's Franklin County.

Florida Gov. Rick Scott said Sunday that such storms were "unpredictable," but he appeared to be preparing for the worst. On Saturday, he declared a state of emergency in 67 counties, and more than 5,000 National Guard members were ready for deployment.