Residents in several states suffer power outages and heavy flooding as officials warn of ‘very dangerous environment’

• Hurricane Helene – live updates

Helene has reportedly killed at least 40 people across four states and inflicted about 4m power outages and dangerous flooding across the south-eastern US after crashing ashore in north-western Florida late on Thursday as a potent category 4 hurricane.

The storm – which registered maximum sustained winds of 140mph – weakened to a tropical storm and then to a depression as it moved across Georgia as well as the Carolinas on Friday afternoon, when residents whose communities experienced Helene’s peak effects more directly were only just beginning to fathom the recovery process ahead.

Forecasters warn that storm, one of the most powerful to hit the US this year, could create a ‘nightmare’

• Tell us: have you been affected by Hurricane Helene?

Hurricane Helene strengthened to a catastrophic category 4 storm as it barreled toward Florida’s Gulf coast, making it one of the most powerful storms to hit the US this year.

The storm is expected to make landfall on Thursday night. Forecasters warn the enormous storm could create a “nightmare” scenario, with a potentially life-threatening storm surge that could reach 15-20ft (4.6-6.1 meters) in the Big Bend area of Florida’s Panhandle region.