MONTERREY, Mexico—A surge of drug violence in Mexico's business capital and richest city has prompted an outcry from business leaders who on Wednesday took out full-page ads asking President Felipe Calderón to send in more soldiers to stem the violence.

The growing violence in Monterrey, long one of Mexico's most modern and safe cities, is a sign that the country's war against drug gangs is spreading ever further from poorer battlegrounds along the border and into the country's wealthiest enclaves.

Residents opened their newspapers Wednesday morning to find the ads taken out by Mexican business leaders, begging the government to send more military into the city. "Enough already," said the notice that ran in national and local papers, criticizing what it said was a slow response of police against "criminal bands that in every act look to establish a new boundary of terror."

Later that day, the body of Edelmiro Cavazos, mayor of the Monterrey suburb of Santiago, was found beside a highway. Mr. Cavazos had been abducted Sunday night, the latest in a string of attacks against politicians in Mexico's north.

His killing is another incident in a terrifying spell for Monterrey residents that began Saturday when armed gangs set up more than a dozen roadblocks on key boulevards of the city, paralyzing traffic for hours. The next day, a grenade was lobbed at the offices of an important television broadcaster. On Tuesday night, grenades were also hurled at several small businesses on the city's outskirts.

"The security environment in Monterrey has turned, in just a few months, from seeming benevolence to extreme violence," U.S. Ambassador to Mexico Carlos Pascual said at a recent conference on drug trafficking in El Paso, Texas.

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