KANDAHAR, Afghanistan — Ten police officers in the southern Afghan province of Oruzgan were poisoned by a rogue colleague and shot in the head by Taliban fighters the officer was working with, the second insider attack on the police in the province in less than two weeks, officials said Tuesday.

The recent insider attacks have added to the woes of an Afghan security force that suffered record casualties in the past year as the Taliban mounted strong offensives across the country, stretching the government’s fighters thin. Officials say the situation in several districts of Oruzgan is fragile, as it is in neighboring Helmand Province, with government operations unable to break the Taliban momentum.

The latest attack occurred late Monday night in the Chermistan area of the Chinarto district, said Faiz Mohammad, the district chief. A police officer who had forged ties with the Taliban poisoned the 10 officers and invited Taliban fighters to the post; they then shot the poisoned men in the head, he said.

“They burned the check post and a police vehicle, and also took the weapons with them,” Mr. Mohammad said. “The police officer who paved the way for the Taliban managed to escape with the Taliban.”