Uber rolls out panic button The feature was announced in the wake of several alleged sexual assaults.

Uber's new panic button has hit phones nationwide.

Announced in April in the wake of a spate of alleged sexual assaults, the panic button allows riders to dial 911 directly from the Uber home screen.

"While no one should ever have to call 911 when using Uber, no form of transportation is 100 percent free of incidents," CEO Dana Khosrowshahi wrote in a blog post at the time. "If ever faced with an emergency situation, we want to help you get the help you need."

In most cities, the app will display the rider's location, which updates in real time, so they can relay their location to 911 operators.

In a handful of cities participating in a pilot program — Denver, Charleston, Chattanooga, Naples, Tri-Cities, Louisville, and, in the next few days, Nashville — the app will automatically transmit location information and vehicle details, including color, make, model, year, and licence plate number, to emergency dispatchers.

"Every second counts in an emergency," Sachin Kansal, Uber's Director of Safety Products, said in a statement to ABC. "We want to make sure our users get help quickly with accurate information if faced with an emergency situation."