A suicide bomber has struck outside an army recruitment centre in Baghdad.At least 21 people are reported dead. Many others are injured.Police said the target was a truck carrying young men into the base.The bomber is believed to have been on foot.It makes this the deadliest attack since last month’s historic election in Iraq. The al Qaeda wing in Iraq, led by Jordanian Abu Musab al-Zarqawi, has claimed responsibility for the massacre.Security forces have borne the brunt of attacks by insurgents.Elsewhere in the capital, gunmen ambushed the convoy of an Iraqi politician. Mithal al-Alusi survived. His two sons and a bodyguard did not.Al-Alusi was criticized after visiting Israel last year. He stood as a candidate in Iraq’s landmark vote on January 30.