Nevada Gov. Brian Sandoval (R) formally declared a state of emergency in Clark County late Monday after a man armed with an arsenal of high-powered rifles killed 59 people and wounded hundreds of others at a concert on the Las Vegas Strip.

The order directs all state agencies to supplement Clark County and Las Vegas law enforcement and health agencies working to save victims of the attack.

ADVERTISEMENT Sandoval also signed a separate order declaring a public health and medical disaster. That order suspends some state medical rules to allow doctors and nurses from other states to temporarily practice in Nevada.

Sandoval appeared shaken at a press conference Monday alongside city and federal officials, who offered an update on the investigation into the nation's deadliest mass shooting.

"My heart and prayers go to the victims and their families and friends who were brutally killed and injured by a shocking and cowardly act of senseless violence," Sandoval said in a statement Monday .

The attack on a country music concert northeast from the Mandalay Bay Resort and Casino, where the shooter was firing from, sent hundreds of people to hospitals around the Las Vegas area, overwhelming emergency rooms and trauma centers.

Sunrise Hospital and Medical Center, the trauma center closest to the concert venue, treated 180 patients, 30 of whom needed surgery, the Las Vegas Review-Journal reported. One doctor told the paper the center had 30 operating rooms working on patients at once.

The Valley Hospital System, a network of six hospitals around the Las Vegas area, treated a total of 228 patients. Three St. Rose Dominican Hospitals treated 57 patients, including four in a level three trauma center who were in critical condition.