A Sunday evening shooting at the Route 91 Harvest Festival in Las Vegas has left as least 50 dead and over 400 injured in what's being called the deadliest mass shooting in modern US history. 

According to Las Vegas police, a gunman located on the 32nd floor of the Mandalay Bay hotel fired into the crowd of about 30,000 people. When the gunshots began, country music singer Jason Aldean was performing. 

Police have identified the shooter as 64-year-old local resident Stephen Paddock. During the shooting, police encountered Paddock at the hotel, where he was pronounced dead. 

“We believe the individual killed himself,” said Sheriff Joseph Lombardo of the Las Vegas Metropolitan Police Department on CNN.

After the shooting was first reported, several SWAT teams went to the Mandalay Bay hotel just after 10 p.m. Las Vegas police reported that “one suspect is down” shortly before midnight and no other active gunmen were reported.

The Las Vegas police said Monday that 50 people were killed and 406 people had been taken to the hospital. Sheriff Lombardo told the New York Times the Las Vegas police were searching for “a companion” of the shooter named Marilou Danley.

Authorities have since announced they were “confident” they had located her. She is not being named as a suspect but has been sought for questioning. 

President Trump has sent his condolences to the victims of the shooting and their families. Former president Obama has also tweeted his "thoughts" and "prayers."