Police said the blast occurred in the northwestern Shia district of Kadhimiya. No more details were immediately available.
Earlier, 19 people were killed and more than 40 wounded in two bombings in eastern Baghdad.
The first blast hit a police patrol in the New Baghdad area on Thursday. Two policemen and four civilians were killed.
An hour later, shortly after Nuri al-Maliki, the prime minister, announced that Abu Musab al-Zarqawi had been killed, a bomb exploded at the entrance to a busy fruit market in the same area.
Thirteen people were killed and several shops were severely damaged.
Al-Zarqawi has been blamed for some of the bloodiest attacks in Iraq, including a campaign of bombings, beheadings and assassinations.
US officials hailed the killing of the Jordanian-born fugitive but have warned that his al-Qaeda group still posed a threat.