"This is a very difficult time, perhaps the most difficult in the recent history of Nuevo Leon" state, Gov. Rodrigo Medina said.

Monterrey Mayor Fernando Larrazabal, for his part, said the cities in the metro area have been overwhelmed by organized crime groups and lack the "capacity and armament" to deal with them.

The surge in violence is hurting the hospitality industry, which has seen average hotel occupancy rates fall as low as 41 percent in 2010, while the average occupancy rate for the year was 60 percent.

The war between the Gulf and Los Zetas cartels left more than 670 people, including a record 75 police officers, dead in Nuevo Leon last year.

The Monterrey metropolitan area, which is made up of nine cities with a total population of 4 million, has experienced about 50 attacks involving grenades and bombs, including a car bombing, against police stations.

The city is also being plagued by so-called "narcoblockades" in which members of youth gangs recruited by drug cartels use trucks, automobiles and buses to block some of the main thoroughfares and slow army deployments.

Cemex, the world's third-largest cement company, is among the industrial corporations that call Monterrey home.

Alfa, the world's No. 1 producer of aluminum engine heads and blocks, Femsa, Coca-Cola's second-largest bottler, and Vitro, North America's biggest glass producer, are among the other industrial powerhouses that have headquarters in the city.

Drug-related violence has also affected the political class.

The Aug. 15 kidnapping and murder of Santiago Mayor Edelmiro Cavazos rocked Mexico and "made clear the relationship between municipal police commanders and the cartels," Autonomous University of Nuevo Leon researcher Jose Juan Cervantes told Efe.

Santiago police officers, who make less than $400 a month, guarded and assisted the hired guns who killed the mayor, providing yet another example of the corruption that plagues Mexico's police departments.

"The gangs became powerful thanks to the fact that they were able to buy the municipal and state police," Cervantes said. "The perception of public opinion is that if the army, the last dike against organized crime, was not here, we would be worse off than Ciudad Juarez."

Cavazos's murder was the last straw for many in Nuevo Leon society and the anxiety caused by the killing drove many wealthy businessmen to move their residences to cities in Texas, which is about 200 kilometers (124 miles) from Monterrey.

The flight of rich families sparked a debate in the business community, with Cemex chief Lorenzo Zambrano calling those who left Monterrey "cowards" for not "defending what was constructed at great effort" by their ancestors.

Instead of improving, the situation has worsened at the start of 2011, forcing officials to admit that the city is dealing with the worst crisis of the modern era.

The high crime in the Monterrey metropolitan area is affecting competitiveness, with Nuevo Leon's economic output dropping 9.4 percent in 2009, Colegio de Mexico researcher Gustavo de la Garza said.

Monterrey, moreover, grew at a slower rate than the country as a whole for the first time since 1980.

State officials, however, contend that the drug war has not affected the business community.

Monterrey and its metro area continue to expand, creating a record more than 95,000 jobs and attracting an all-time high of $2.2 billion in foreign investment in 2010, Nuevo Leon state security spokesman Jorge Domene told Efe.