The attack comes a day after Hussein's defense lawyers called for the trial to moved outside of Iraq to protect their lives.
The defense team made that call after increasing threats since the murder of a colleague a day after the trial started. On 20 October, the body of another lawyer, Sad'un al-Janabi, who was defending Ba'ath Party official Awad Hamad Bandar Sa'dun, was found in Baghdad one day after he had been abducted from his home by a group of armed men.
A court in Baghdad is trying Hussein and seven co- defendants for alleged crimes against humanity. They could all be executed if found guilty.
The trial has been adjourned until 28 November.
A slideshow of photographs from Saddam Hussein's years ruling Iraq through his downfall.