File Photo: Security personnel inspect the wreckage of a vehicle at the scene of a blast in Aden. AFP
A car carrying explosives detonated while the convoy of a security official from a neighboring province was driving by, the officials said.
Three of his guards were wounded in the explosion.
The officials said two security personnel died later from their wounds, bringing the death toll to at least six people, including four civilians.
The top security official for Lahj province Brig. Gen. Saleh Sayed was not seriously hurt, added the officials, who spoke on condition of anonymity because they were not authorized to brief the media.
Videos from the scene showed the dead and injured lying in a minibus, while a cloud of black smoke rose from the explosion site.
The bombing was the latest to target security officials in the key port city, which serves as the headquarters of Yemen's internationally recognized government.
Aden has been the seat of the government of President Abed Rabbo Mansour Hadi since the Iran-backed Houthi rebels seized the capital of Sanaa in 2014, triggering the country's protracted civil war.
There was no immediate claim of responsibility for the attack. The city has been rocked by frequent bombings in recent years blamed on local affiliates of al-Qaida and the Islamic State group.
The Houthis have also targeted the city with ballistic missiles and explosives-laden drones.