Afghan soldier attacks USA troops

"We can confirm there are no USA or NATO Resolute Support fatalities", NATO said in a statement.

Four more attackers stormed the gate after the blast, with at least two quickly killed by police.

Taliban took responsibility of the incident and said that Afghan soldier who killed USA soldiers belonged to Taliban group.

Afghanistan's Ministry of Defense also is investigating, said Abdul Qhahar Aram, head of strategic communication and public affairs for the 209 Shahin Corps.

An Afghan soldier opened fire on USA troops on Sunday, wounding at least seven, the US military said. The attacker was shot and killed when soldiers returned fire.

Another attack on June 17 left seven USA troops wounded.

Sseven US servicemen were wounded and one Afghan soldier was killed in an insider shooting at a base in northern Afghanistan.

"The Taliban have been able to bring in soldiers into the Afghan army and make them sleepers, as it were, until the right time", journalist Ahmed Rashid told Weekend All Things Considered in April.

"On my way here I was informed that USA service members were killed and wounded in an attack in Afghanistan", Pence said. He could not immediately say if the suspected shooter was among the dead or wounded.

Two months ago the same base came under attack by Taliban insurgents.

The U.S. now has roughly 8,400 troops in Afghanistan (excluding those in country on a temporary basis), while North Atlantic Treaty Organisation and coalition allies have a total of about 5,000 forces.

So-called green-on-blue, or insider, attacks have been a recurring problem for the US -led coalition, most recently on June 10 in the Achin District of eastern Nangarhar province, where USA ground forces are helping Afghan special forces fight Islamic State extremists.