Rescue workers could be seen evacuating casualties, including the body of a child carried away on a stretcher, in footage aired on state television.
Second bridge attack
Police fired into the air to disperse crowds of people and clear the way for more than a dozen ambulances after the bomb exploded.
Meanwhile, in Baghdad, the Iraqi capital, a suicide car bomb exploded on a major bridge on Saturday, killing at least 10 people, police said.
At least 15 people were wounded in the attack, which occurred on the Jadriyah bridge over the Tigris river.
The extent of damage to the bridge was not immediately clear.
The bombing was the second attack on a major bridge in Baghdad this week.
Eleven people were killed when a suicide lorry bomb collapsed the al-Sarafiyah bridge in northern Baghdad on Thursday.