Hajji Abdul Rahman Aka, a village elder, said the insurgents had hidden in a graveyard and were monitoring the movement of the police using night-vision goggles.
“The Taliban attacked the post and did not even give the police a chance to wake up and reach their weapons,” Mr. Aka said. One officer was wounded and escaped, he said: “The rest of the police were killed, still in their beds.”
Mr. Mehri also said that the assailants had used night-vision goggles, adding that the authorities had seen the technology used repeatedly recently. After an army attack on the Taliban two months ago in the Bala Baoluk district of Farah Province, he said, night-vision goggles were found on the bodies of some of the insurgents.
Qari Yusuf Ahmadi, a spokesman for the Taliban in the south and west of the country, boasted of the insurgents’ use of the technology. “Usually we are using laser weapons and night visions on night attacks, and we definitely used night visions and laser weapons for that attack as well,” he said, reached by cellphone at an undisclosed location. He appeared to be referring to laser systems used as gun sights on some weapons.
He added that 13 police officers had been killed in the attack on Monday.
Mr. Mehri said the night-vision goggles found in Farah appeared to be Russian-made. General Waziri said that the military had seen goggles with Russian markings, but that the insurgents probably got them from on the black market in Pakistan. In rarer cases, he said, they may have seized them from Afghan soldiers on the battlefield.
The episode on Monday was believed to be the deadliest on an Afghan National Police unit since Oct. 17, when two attacks killed more than 40 officers, including a police general. Two days later, a powerful car bomb hidden in a captured military vehicle wiped out most of an entire army unit, killing 49 soldiers.
The authorities said there was no evidence that the surviving police officer was an infiltrator, but insider attacks have plagued the Afghan police in the past. Mr. Ahmadi denied that an infiltrator was involved.