The death toll could rise after a final assessment, added Zwak. As many as 40 security forces may have been killed, according to a provincial official who spoke anonymously as he was not authorized to brief the media.
Zwak added that military vehicles and offices were damaged by blasts and shooting in the attack. Qari Yusouf Ahmadi, a Taliban spokesman, said in a statement that the insurgent group was responsible for the attack, which came even as Taliban negotiators met for talks with a U.S. peace envoy in the Middle Eastern state of Qatar.
He said Taliban fighters engaged both Afghan and foreign forces inside the camp and killed "scores." Zwak said U.S. advisers were present in the base, but in a separate area. "The foreign forces present at the base were all safe as the Taliban could not reach that part of the compound," he said.
Zwak said the attack began when a suicide bomber detonated his explosives at Shorab camp. He said three other suicide bombers also blew themselves up as gunmen followed behind them. Zwak said 22 Taliban gunmen were killed in the fighting.
In recent years, the Taliban and the Islamic State group have carried out near-daily attacks in Afghanistan, mainly targeting the government and its security forces. The Taliban control several district centers in Helmand, which is a major source of the world's illegal opium supply.
Camp Shorab was previously a British air base known as Camp Bastion. In northern Sari Pul province, Taliban ambushed a convoy of Afghan security forces, killing nine, said Zabihullah Amani, spokesman for the provincial governor.
Amani said 12 other forces were wounded during the battle with insurgents that lasted seven hours Friday in Sangcharak district. "Four security forces are missing and believe to be taken alive by the insurgents," he said.
The forces were just returning from an operation in the district when they came under heavy fire, Amani said. Zabiullah Mujahid, a spokesman for the Taliban, claimed responsibility for the attack.