Fun goers at a Route 91 Harvest Country Music festival at Mandalay Bay Casino in Las Vegas, were attacked by an unknown gunman, who has an automatic weapon, while country singer, Jason Aldean was performing. According to eyewitness, they heard several shots and it seemed like the shooter was shooting from an elevated position. As soon as the shooting started, concert goers tried to take cover, while others panicked and tried to run out of the venue, causing a stampede. An eyewitness said he saw a woman who was beside him get shot in the head. The police and Ambulance are now at the scene, taking the wounded to the hospital. The gunman is still at large. There's a lockdown on the strip right now, while the Police and SWAT conduct searches. Story still developing.. Witnesses describe the attack Mark Mullen -- who was staying on the 29th floor of the Mandalay Bay hotel -- told ABC News that when the shots broke out, he was sitting in his room and listening