An unknown number of gunmen shot Nuevo Laredo's (search) new police chief at least 35 times and killed him Wednesday only hours after he took the post, officials said.

Alejandro Dominguez (search), a businessman who once worked at the federal attorney general's office and was a cousin of ex-Attorney General Javier Coello Trejo (search), told reporters upon assuming control of the city's police force that he wasn't afraid of anything, even though many police chiefs here have met violent ends recently.

"I don't owe anybody anything, my duty is to the citizenry," he said. "I think those who should be afraid are those who have been compromised."

Hours later, a group of assailants opened fire on Dominguez as he was climbing into his Ford Lobo truck outside the city's National Business Chamber (search), of which he was the director.

The shooting happened around 11 p.m., according to Fernando Vallejo, director of ministerial police for Tamaulipas state, which includes Nuevo Laredo, across the border from Laredo, Texas.

"We've recovered 35 to 40 casings from an AR-15 assault rifle," Vallejo said.

A witness told authorities Dominguez was targeted by a group of men who arrived at the scene of the shooting in three dark-colored Chevy Suburbans.

Also on Wednesday, seven gunmen wearing ski masks entered a hospital in a northern Mexican state capital and killed a federal agent who was recovering there from gun shot wounds, investigators said.

The assailants, who also killed two men accompanying the agent, arrived at the Clinica del Centro hospital in Chihuahua City (search), just after 1 a.m.

After subduing security guards and covering surveillance cameras, the group moved into the room of federal agent Victor Estrada, said Rene Medrano, a spokesman for Chihuahua state attorney general's office.

A former member of the federal judicial police force, Estrada was an 11-year veteran of the Federal Agency of Investigation who was suspended for vague investigative violations and reinstated in early March at the order of a Chihuahua judge, federal authorities said.