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'America's toughest sheriff' Joe Arpaio hunts colleague's killer

Matt York / AP

Maricopa County Sheriff Joe Arpaio pauses while speaking about a detention officer who was shot early Thursday.

PHOENIX, Ariz. -- An Arizona detention officer who worked for the jail system run by America's self-described "toughest sheriff" was shot and killed in the driveway of his Phoenix home as he prepared to go to work before dawn on Thursday, authorities said. 

Maricopa County Sheriff via AP

Jorge Vargas, 27, was shot to death in his driveway while preparing to leave for work early Thursday.

Police officers using dogs mounted a two-hour search of the residential neighborhood after the shooting of the officer, who authorities said had been wearing clothing with a sheriff's office insignia on it. There was no immediate word on motive. 

"We will certainly look into whether it was related to his duties, but at this point we don't know," Phoenix police spokesman Sergeant Trent Crump said. No arrests have been made. 

Witnesses reported they heard several shots fired at about 4 a.m. and spotted a man fleeing the scene on foot, police said. Television footage from the scene showed a pick-up truck in the driveway with its hood up and the driver's door open. 

When authorities arrived at the scene, they found the officer severely wounded in front of the home. He was later pronounced dead at a local hospital. 

The officer was identified as Jorge Vargas, 27, an eight-year veteran with the Maricopa County Sheriff's Office. He worked in the system's food factory, which is responsible for the management and distribution of food throughout the jails. 

Sheriff Joe Arpaio told a news conference that he does not know the motive for the killing, or whether the officer was targeted. 

"Right now the main mission is to find this guy and get him in jail," Arpaio told reporters. 

Arpaio, 81, has been a lightning rod for controversy over his aggressive enforcement of immigration laws. The six-term sheriff has been the subject of several investigations and lawsuits stemming from his get-tough policies.