Dozens of Taliban fighters and suicide bombers have attacked a US military base in eastern Afghanistan, officials said.
At least 13 people were reportedly killed on Tuesday, some in their own suicide blasts.
The Nato-led International Security Assistance Force (Isaf), confirmed that Camp Salerno in the eastern town of Khost, 30km from the border with Pakistan, had been attacked but could give few details.
"We have heard about suicide bombers on foot. They are receiving indirect [rocket and artillery] fire," said an officer in the ISAF media office in Kabul, the capital.
A suicide car bomb at the base on Monday killed 10 Afghan laborers waiting outside.
Security forces were able to prevent a second suicide attack moments later, according to the US-led coalition and Afghan officials. The Taliban had claimed responsibility for that attack.
General Mohammad Zahir Azimi, the Afghan defense ministry spokesman, said 15 "terrorists" had attacked the base on Tuesday.
"Our commando units were deployed into the area and engaged the attackers and pushed them back," he said.
"So far 13 attackers have been killed. Six blew themselves up, six others died in the explosions and one died in gunfire from commandos. Their bodies have been recovered."
Al Jazeera's Zeina Khodr, reporting from Kabul, said that local and international security forces are launching an operation to capture the remaining fighters involved in the attack.
Conflicting reports
An Afghan army officer said on condition of anonymity that four US soldiers had been wounded. This could not immediately be confirmed by the US military.
Arsala Jamal, the governor of Khost, said his information was that "about 30 Taliban tried to attack the Salerno base".
"They were fired at. We have found six bodies which were all wearing suicide vests," he said.
"Some of them have blown themselves up. Others are hiding in nearby houses and corn fields. The troops are searching for them."
Jamal also said that four Afghan army troops had been wounded in the fighting,
According to an Afghan army officer, the attackers had also launched rockets at the base.
PHOTO CAPTION
Map locates Khost, Afghanistan, where suicide bombers attacked U.S. base.
Al-Jazeera