By Madison Park, Joe Sutton and Joe Sterling, CNN

(CNN) -- Two people died Wednesday after severe weather caused a landslide in western North Carolina.

Another two people are missing in north-central Virginia. Flood water swept away their Toyota Prius in Albermarle County, according to county authorities.

Around 9:30 Wednesday, Ivy Creek topped its bank, creating a flash flood that swept away the Prius and another car. The occupant of the second car was rescued, a county news release said.

Heavy rains pummeled the western part of North Carolina on Tuesday and Wednesday, causing mudslides and forcing evacuations and road closures.

Two people were found dead in the rubble of a home in Boone, North Carolina, according to the Boone Fire Department. A landslide caused a gas explosion that leveled the house, said Shane Robbins, the Boone Police Department spokesman.

The incident marked the fourth weather-related deaths attributed to Alberto, which made landfall earlier this week as a subtropical storm and has since drenched the states in its path. On Monday, two journalists from South Carolina-based CNN affiliate WYFF were killed in Polk County, North Carolina. A tree fell on their SUV as they covered the hazardous weather, the station said.

The weather conditions prompted North Carolina Gov. Roy Cooper to declare a state of emergency Wednesday for the western part of the state.

"This storm isn't yet over. I'm urging people to keep a close eye on forecasts and flood watches, and asking drivers to use caution especially when traveling in our western counties," Cooper said in a statement Wednesday.

The emergency declaration will help the state coordinate its response and "prepare for any additional impacts," the statement said.

In the last 24 hours, 4 to 7 inches of rain slammed parts of a region that had been hit by frequent rain for a couple of weeks. And in the next couple of days, there will be a threat of flash flooding as storms persist, the governor's office said.

Landslides, flooding and outages

The North Carolina Department of Transportation has been assessing damage and removing debris caused by mudslides, washouts and flooding on interstates, highways and local roads.

Several towns in western North Carolina reported high water levels, power outages, downed trees and blocked roads.

The city of Asheville reported road and park closings and school delays Wednesday. It is managing water releases from the North Fork Reservoir Dam.

Alberto made landfall Monday as a subtropical storm in the Florida Panhandle and weakened to a subtropical depression later that day. But it brought heavy rainfall, drenching parts of northern Georgia, the western Carolinas and Tennessee on Tuesday, increasing the threat of flash flooding in those areas, the National Weather Service said.

After moving into the Tennessee Valley, the system is forecast to head into the Ohio Valley and Great Lakes region Thursday, according to the National Hurricane Center.

Florida, Mississippi and Alabama -- the three states bearing the brunt of the storm -- declared emergencies ahead of Alberto.

Click here to track the storm

Hurricane season is set to begin officially Friday.