KABUL. AFGHANISTAN (CNN) -

Gunmen attacked a spy agency in eastern Afghanistan early Saturday, killing six people and leaving dozens injured, authorities said.

The Taliban militant group claimed responsibility for the attack in Jalalabad city.

It targeted the provincial headquarters of the national directorate of security in Nangarhar province, according to Hazrat Hussain Mashriqiwal, a local police spokesman.

The attack started with a suicide bombing involving an explosives-laden truck and two assailants at the gate of the compound, he said.

Six more attackers armed with guns and hand grenades then stormed into the building and battled with security forces for hours.

All six assailants were killed, according to the spokesman.

Most of the 45 people wounded are nearby residents injured by smashed windows or collapsed ceilings as a result of the suicide bombing, said Dr. Najibullah Kamawal, the province's top health official.