Heat wave forecast: DC National Mall events disrupted, NYC power grid strained

 A dangerous heat wave is bringing prolonged extreme heat to more than two dozen states across the Midwest, the South and the East Coast into the Fourth of July weekend.

Although the holiday travel rush is in full effect, the heat led Amtrak to cancel more than two dozen trains in the Northeast.

In Washington, D.C., the Great American State Fair abruptly closed midday Friday due to the dangerous temperatures, organizers said. Organizers said the fair was set to reopen at 5 p.m.

D.C. Fire and EMS told ABC News that crews treated 44 patients on the National Mall on Friday, transporting 11 people to local hospitals.

Officials stressed that not all of those cases were heat-related, noting that some patients were treated for injuries and other medical issues unrelated to the extreme temperatures.

In Washington, D.C., the Great American State Fair abruptly closed midday Friday due to the dangerous temperatures, organizers said. Organizers said the fair was set to reopen at 5 p.m.

D.C. Fire and EMS told ABC News that crews treated 44 patients on the National Mall on Friday, transporting 11 people to local hospitals.

Officials stressed that not all of those cases were heat-related, noting that some patients were treated for injuries and other medical issues unrelated to the extreme temperatures.