Picture gallery: US inferno

More than 20,000 firefighters are struggling to tackle fires in 11 US states in what is considered the worst such outbreak in 50 years.

More than 62,000 wildfires have been reported from Canada to Mexico

Lightning bolts are the perfect spark for wildfires

A firefighter tries to cool down amidst the intense heat

An air tanker drops fire retardant over one of the more than 60 fires

A sunset in Sequoia National Forest where the fire is out of control

Extra training is necessary for those wanting to help out

Even experienced firefighters could be overwhelmed

Firefighting helicopters are vital to the operation