Three suicide bombers who wanted to attack Kandahar’s National Directorate of Security were killed by security forces early on Wednesday, local officials said.

The incident took place in Kandahar city, when the bombers attacked the security guards of the department and started clashing with them. One NDS security guard and a female employee of the department were injured in the attack, said Deputy Security Head of Kandahar Police, Rahmatullah Atrafi.

“We found Pakistani documents on the bodies of the insurgents which showed they came from Pakistan,” he said.

The police have started investigations about the incident, he said.

No group including the Taliban has claimed responsibility for the attack.

An eyewitness said that four bombers clashed with security forces.

Kandahar province borders Pakistan and the insurgents frequently target the Afghan security forces.