The attackers struck a crowd of workers leaving the huge complex in Wah, near Islamabad, after their shift.
Prime Minister Yousuf Raza Gilani strongly condemned the attack and 'directed the authorities to make efforts to expose the hidden hands behind the incident.'
A spokesman for Tehreek-e-Taliban Pakistan, the umbrella group for the country's Taliban Islamist militants, said it was responsible.
The Taliban threatened to carry out further suicide attacks if an army offensive against militants near the Afghan border is not stopped.
The Pakistani Ordnance Factories at Wah is a cluster of about 20 industrial units producing artillery, tank and anti-aircraft ammunition for the Pakistani armed forces. It employs 25,000-30,000 workers.
The blasts came two days after a suicide bomber attacked a hospital in the northwestern town of Dera Ismail Khan, killing 30 people.
