KANDAHAR, Afghanistan -- Four coalition soldiers were killed Sunday in southern Afghanistan, the American-led international military force said, in the coalition's worst loss of life in a single episode since June.
The episode took place in the Zhari district, in Kandahar Province, said Javed Faisal, the spokesman for the provincial governor.
The International Security Assistance Force said in a statement that the four soldiers were killed "by enemy forces during a partnered operation." It gave no further details. The coalition did not identify the nationality of the victims pending notification of their next of kin, but nearly all coalition soldiers in Zhari are Americans.
Jamal Agha, the district governor of Zhari, said the deaths took place in a fight between insurgents and a joint operation involving coalition and Afghan commandos. Mr. Agha said the deaths were caused by a booby-trapped bomb.
A spokesman for the Taliban, Qari Yousuf Ahmadi, said the insurgents had placed a bomb in a house and detonated it when the coalition soldiers entered. When the soldiers' comrades came to their aid, a suicide bomber hiding elsewhere in the house detonated his explosives.
The last time as many as four coalition soldiers were killed was on June 18, when insurgents launched a rocket attack on the Bagram Air Base north of Kabul. The soldiers killed in that attack were all Americans.
In a separate episode on Saturday, a service member was shot dead "when an alleged contracted security guard shot the service member," the coalition said.
Afghan officials said that the attack took place at Forward Operating Base Apache in Qalat, the capital of Zabul Province in southern Afghanistan. According to the provincial chief of security, Ghulam Jilani Khan, a private Afghan security guard had a dispute with an American soldier and killed him. Other soldiers then killed the attacker, he said.
Casualties among coalition forces have sharply dropped this year, as Afghan security forces take over most of the fighting, and the number of foreign troops has decreased. Partnered operations like the one on Sunday have become relatively rare, except among Special Operations troops. American and other coalition advisers often accompany Afghan units in the field, as well.
According to the independent monitoring group iCasualties.org, 136 coalition soldiers have been killed so far this year, 106 of them Americans, the lowest rate since 2007.
Taimoor Shah reported from Kandahar, and Rod Nordland from Kabul, Afghanistan.
Correction: October 6, 2013, Sunday
This article has been revised to reflect the following correction: An earlier version of this article, using information from an Afghan official, Ghulam Jilani Khan, referred incorrectly to the Afghan security guard who Mr. Khan said had killed an American soldier. The Afghan is not employed by DynCorp International, an American company that provides security-related services at many American bases.
This article originally appeared in The New York Times.