Suspected drug cartel gunmen have stormed a bar and shot dead at least eight people in the northern Mexican city of Monterrey in an apparent dispute over drug dealings.
Four victims died on site in the Matehuala bar, a well-known venue in the city centre, and four more died later in the hospital, officials said on Tuesday.
Six gunmen arrived in three vehicles, entered the bar and began shooting in the latest brutal incident in a wave of recent violence across Mexico that have been blamed on drug gangs.
Witnesses said the attackers identified themselves as members of the Gulf cartel, which operates in northeast Mexico, before they opened fire, Nuevo Leon public security spokesperson Jorge Domene told local radio.
"These are dives, illegal bars where there could be some drug dealing, that's one of our main lines of investigation," he
said on Milenio television.
Mexico's most afluent city, Monterrey, is the capital of Nuevo Leon state and was long been seen as a model of economic development in Latin America. But it has been ravaged by drug warfare over the last three years.
In May, 49 headless bodies were dumped near the city and 52 people died in an arson attack on a casino in August last year.
Both attacks were blamed on the notorious Zetas drug gang, which is waging a war against rival groups for control of
smuggling routes into the US, the world's biggest market for illicit drugs.
All the bar victims were male and six were identified as employees of the bar.
Domene said the attack seemed similar to a massacre last year in Monterrey, where 21 people were gunned down in a bar where employees were allegedly selling drugs.
The Zetas, who are blamed for many of the most brutal attacks seen in Mexico's drug conflict, were founded by Mexican army deserters who became enforcers for the Gulf cartel, which once dominated the drug trade in northeastern Mexico.
Leaders of the Zetas later split from their employers and have since fought their former bosses as well as other groups, such as the Sinaloa cartel.
There has been a rash of deaths and violence since last week in central and northern Mexico, prompting the government to send in extra troops and armoured vehicles to the states of San Luis Potosi, which borders Nuevo Leon, and Michoacan.
A mayor elected in Mexico's July 1 election and his campaign manager were found shot dead in a truck on Sunday morning in San Luis Potosi and a family of seven, including three young children, were found dead in their home that day.
A running battle between federal troops and suspected drug gang members on Friday in Michoacan killed nine.
More than 55,000 gangland murders and execution-style hits have occurred since President Felipe Calderon took power in December 2006 and declared a national crackdown on drug gangs.