At least five people were trampled to death on Sunday when concert fans were panicked by the sound of gunfire and caused a stampede in this northern city, which has been on edge since drug violence flared in recent weeks.
Hundreds of fans of the Norteno group Intocable at the show rushed for the exits after some people yelled that they had heard shooting, senior government official Ivonne Alvarez told reporters.
Television images showed people giving mouth-to-mouth resuscitation to unconscious and half-naked men and women scattered around one of the venue's exits. Police later recovered one spent bullet shell.
Video recorded on a cellphone and broadcast on Milenio television showed bewildered concert-goers ducking behind their chairs as somebody repeatedly yelled, "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 trucks and buses in an attempt to hamper army operations near the U.S. 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.
About 160 people were killed in drug-related violence in Monterrey and the surrounding state of Nuevo Leon between January and April, according to local media, more than in the previous two years combined.