Utility crews across the Florida Panhandle and southern Alabama were working Monday to restore electricity to hundreds of thousands of customers who lost power when Hurricane Isaias came ashore Friday night.

More than 390,000 customers were still without power as of Sunday morning, NPR reported. Florida Power & Light, the state's largest utility, said it aimed to restore 95% of affected customers by the end of Monday, Fox Weather reported.

At least four people have died, two in Florida and two in Alabama, according to The Associated Press. In Alabama, one person was killed when a tree fell on a house in Jefferson County and another died in a crash involving a downed tree in Barbour County, state officials said.

Officials are urging residents to stay away from downed trees and power lines. They also warned against running portable generators indoors or in garages because of the risk of carbon monoxide poisoning, AccuWeather reported.

Isaias made landfall near Destin, Florida, as a Category 2 hurricane with top sustained winds of 105 mph, the National Hurricane Center said. It weakened quickly and was a post-tropical cyclone by early Saturday, but not before peeling roofs off buildings and flooding streets along the coast. At the peak, nearly 900,000 customers in Florida, Alabama and Georgia had no electricity, The Washington Post reported.

The storm's remains then moved north, bringing heavy rain and flood warnings to the mid-Atlantic and Northeast on Sunday, according to Fox Weather.

Isaias was unusual for its timing. It became a hurricane last Wednesday, the latest date in 121 years for the first hurricane of an Atlantic season, CBS News reported.

Outage figures are as of Sunday morning. Utilities had not released an updated regional total by Monday morning.