As the number of killed and wounded mounted in Las Vegas Sunday night following a deadly attack, Nevada first responders quickly turned to Arizona for aid.

In one of the deadliest mass shootings in modern U.S. history, Las Vegas first responders raced to save the lives of hundreds of people attending a country music concert after a gunman opened fire from a nearby hotel.

Damon Schilling with AMR Medical Transportation in Las Vegas said they immediately looked to Arizona for help.

“Our regional director got on the phone with the regional director of Arizona, gave him a brief description of what’s going on, and without hesitation, immediately dispatched several units from Arizona that were on their way to help,” Schilling said.

Units responded from Prescott, Kingman and Lake Havasu City.

They staged near the Las Vegas Strip to assist with routine calls while local responders dealt with shooting victims. Schilling said Las Vegas now has sufficient resources and the ambulances have since headed back to Arizona.