KABUL, Afghanistan -- A female police sergeant shot and killed a U.S. civilian adviser at police headquarters in Kabul on Monday, Afghan police officials said, breaking a relative lull in the so-called insider killings that have strained the relationship between Americans and Afghans here.

The American victim was identified as Joseph Griffin, 49, of Mansfield, Ga., who had worked for DynCorp International as a police trainer since July 2011, according to a DynCorp spokeswoman, Ashley Burke.

Afghan officials identified the shooting suspect as a woman named Nargis, a 33-year-old sergeant in the national police force who worked in the Interior Ministry's legal and gender equality department, and whose husband is also a member of the police force.

A person at Kabul police headquarters, speaking on condition of anonymity because he was not authorized to release information, said the attacker had shot the U.S. adviser in the head at close range with a pistol and then was immediately arrested by other Afghan police officers.

Police said they did not believe the attack was related to terrorism and that the suspect had no known connections with insurgents.

The Afghan news station TOLO cited Afghan officials as saying that the woman, who had crossed multiple police checkpoints before she fired her gun, had graduated from the national police academy in 2008.

The effort to recruit and train female police officers has been fraught with difficulty. EUPOL, the European police organization active in police training here, says there are only 380 female police officers in Kabul, and even fewer in the provinces.

Insider attacks, in which members of the Afghan security services have turned against their foreign allies, have greatly increased in the past year, with 61 U.S. and other coalition members killed, not including the episode Monday, compared with 35 deaths the previous year, according to NATO figures.

Monday's attack -- the first insider attack known to be committed by a woman -- came after a lull in insider shootings.