Las Vegas officials are investigating a deadly mass shooting that left 58 dead and at least 515 injured Sunday night.

Police have identified 64-year-old Stephen Paddock of Mesquite, Nevada, as the gunman responsible for shooting multiple people at the Route 91 Harvest, a country music festival headlined by Jason Aldean.

The Associated Press reported the gunman was found dead when officers used explosives to get into his room at the Mandalay Bay hotel.

Sunday night’s shooting at the Las Vegas Strip is the deadliest mass shooting in modern U.S. history.

Here are seven things to know about the Route 91 Harvest:

What is it?

The Route 91 Harvest, called the "neon sleepover," is a three-day country music festival. The 2017 event was the fourth time the festival had been held in Las Vegas.

It took place at the 15-acre Las Vegas Village (3901 South Las Vegas Boulevard) from Sept. 29 to Oct. 1.

How many people were at the 2017 event?

More than 40,000 country music fans flocked to Las Vegas for the three-day festival.

How much were tickets?

Festival tickets cost $210 for all three days.

According to the official festival website, passes were sold out for the 2017 event.

Who was headlining at the festival?

Several big-name performers made up the 2017 Route 91 Harvest lineup, including Eric Church, Sam Hunt, Jason Aldean and Jake Owen.

You can find the full festival lineup at rt91harvest.com/lineup.

Who was performing Sunday night during the shooting?

Country music star Jason Aldean was performing Sunday night at the end of the three-day festival when the gunman opened fire across the street from inside the Mandalay Bay Hotel and Casino.

It was approximately 10:08 p.m. local time ( 1:30 a.m. EST).

Musicians Luke Combs and Jake Owen took the stage before Aldean.

Have festival officials responded?

Festival officials have not released an official statement.

How about performers?

Some country music stars who performed at Route 91 Harvest have shared their horrific accounts and prayers on social media.

For the latest updates on the Las Vegas shooting, visit AJC.com.

This story has been updated.