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

Dozens of patrol vehicles descended on the famous Vegas Strip after reports of an active shooter near a country music festival late on Sunday.

"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 said.

Witness Cole Watson was at the concert with his wife and kids.

"At first it sounded like someone was setting off a whole lot of firecrackers, but then we realised it was gunfire and everybody started running. The scene was insane - it was absolute chaos," Watson told Al Jazeera.

Some officers took cover behind their vehicles while others carrying assault rifles ran into the Mandalay Bay Hotel and Casino. Concert-goers reported seeing muzzle flashes from its upper floors.

Witnesses fled as gunfire rained down on the concert venue. There were "dead people at the concert right next to me. We crawled over dead people", witness Cari Copeland Pearson told dpa news agency.

Video posted shows a crowd of panicked people huddling together on the street outside of the hotel as automatic weapon fire rang out.

Source: Al Jazeera and news agencies