Police in Las Vegas are investigating reports of a gunman who opened fire at a country music festival near the Mandalay Bay Resort and Casino on Sunday night.

Several media outlets reported that at least one person was seen firing multiple rounds from an assault rifle at the conclusion of the Route 91 Harvests Music Festival. Initial shots were reported around 10:30 p.m., according to News3LV.

At 11:58 p.m., the Las Vegas Metropolitan Police Department (LVMPD) announced that “one suspect is down.”

“Confirming that one suspect is down. This is an active investigation. Again, please do not head down to the Strip at this time,” the police department tweeted.