At least five people were trampled to death when concert-goers panicked at the sound of gunfire and caused a stampede in a city which has been on edge since drug violence flared.

Hundreds of fans at a gig in Monterrey, northern Mexico - who were watching the Norteno band Intocable perform on stage - rushed for the exits after a few concert-goers said they had heard shooting. Television images showed people giving mouth-to-mouth resuscitation to unconscious concert-goers at one of the venue's exits. Police later recovered one spent bullet shell. Video recorded on a mobile phone, and broadcast on Milenio television, showed people ducking behind their chairs as somebody repeatedly shouted: "Get down!"

Considered one of Latin America's premier business cities, Monterrey has been engulfed by violent crime as battles between rival drug gangs spill into once-tranquil parts of Mexico, alarming Washington, foreign investors and tourists. In March, armed men, probably linked to drug gangs, blocked highways around the city with lorries and buses in an attempt to hamper army operations near the US border.

The same month two university students were killed when they were caught in the crossfire between soldiers fighting gunmen near one of Mexico's most prestigious universities.