A motorbike rigged with explosives exploded near a large hospital in Basra city, Iraq, on Tuesday.
The city's governor, Asaad Al Idani, told The National that at least four people were killed and four wounded in the explosion, which destroyed two cars.
Explosives experts have begun an investigation into the blast, which no group has yet claimed.
The blast happened near the Republican Hospital in the centre of the city, sending columns of black smoke into the sky. Witnesses called for action against the attackers and said the death toll was probably higher than announced.
"Today's bomb was because of a political dispute due to militias losing seats in parliament, I ask Basra governor Asaad Al Idani to reveal the attackers as we want tangible actions to name them," said Abbas Hassan, 23, who was in the area when the bomb went off.
“I am speechless, we are used to living like this situation every four years after elections, and of course Iraqis are the biggest loser.”
Garage owner Abdulkareem Hashim said he was injured by glass from cars damaged by the blast.
“Before 11.30am, a motorbike driver left his motorbike aside and went away. After five minutes we heard a strong explosion, and my left hand and leg were bleeding. I didn't know what was happening at first, then I realised it was a motorbike bomb.”
Iraqi President Barham Salih described the explosion as an attack that was a "desperate attempt to destabilise the country" and that unity was needed.
"We have no choice but to unite and protect our security and peace and punish the perpetrators," Mr Salih said on Twitter.
The country's Security Media Cell, an outlet affiliated with Iraq's security forces, said forensics teams were at the scene of the blast and that more details would be released, once investigations were complete.
The explosion occurred as security forces were involved in a large-scale offensive against ISIS remnants in northern Iraq.
The terrorist group controlled about a third of Iraq between 2014 and 2017, including big northern cities such as Mosul.
Attacks by ISIS in Basra are rare – the last major explosion was in 2017 when a suicide car bomb killed at least eight people at a checkpoint north of the city.
The country has faced political instability since the early parliamentary elections on October 10.
Shiite populist cleric Moqtada Al Sadr turned out the biggest winner, but a coalition of political parties allied to armed groups loyal to Iran fared badly. A number of parties with less than one third of the seats in the Iraqi parliament rejected the results, citing fraud.
Since the 2003 US-led invasion that toppled former dictator Saddam Hussein, Iraq has been torn by years of instability and conflict.