At least 20 people were killed and more than 100 wounded when a gunman opened fire on a country music concert in Las Vegas on Sunday, police said.

"We have in excess of 100-plus injured and excess of 20-plus that have died at this point," Las Vegas Metro Police Sheriff Joseph Lombardo told a press conference.

The gunman, who was a local man, was killed after police "engaged the suspect," Lombardo told reporters