A suicide bomber killed at least four people while blowing himself up near a moving convoy of Somali special forces Sunday, according to a police official cited by the Associated Press. The bomber drove a car packed with explosives into a group of soldiers on the airport road in the capital city, Mogadishu, police Capt. Mohamed Hussein said.

According to Mohamed Yusuf, a representative of Somalia’s National Security Ministry, the explosives denotated while the attacker was being pursued. “We shall continue preventing such attacks. However, we ask people to work with us,” he told reporters.

The attack was directed toward commandos in Somalia’s Alpha Group, a U.S.-trained team that is frequently called to deal with militants in the country. However, the bombing victims were mostly pedestrians on the road, police said.

While no group has claimed responsbililty for the attack, the current security threat in Somalia indicates al-Shabab may have been involved: It might have been carried out in revenge over the terrorist group’s intelliegence chief being killed in a U.S. airstrike days ago, as AP suggested.

Somalia has been in political turmoil since dictator Siad Barre was ousted in 1991.