ADEN, Yemen -- A powerful car bomb ripped through the security headquarters in Yemen's southern port city of Aden early Tuesday, killing at least four soldiers and injuring two others, a government official said.

"The assault came after a suicide bomber struck the security headquarters in Aden's neighborhood of Khor Maksar district with an explosives-laden car at the main gate of the building," the official told Xinhua on condition of anonymity, adding that it was a suicide car bombing.

A security source confirmed to Xinhua that "one suicide bomber detonated a car bomb at the gate of the security center while another two attackers blew themselves up inside the building."

The explosion, which occurred at around 3 a.m.(0000 GMT), destroyed part of the special security headquarters and damaged a number of adjacent buildings, including several residential buildings, local residents said.

The government official said there was no employees inside the security center at the time of the blast so the number of casualties was not high.

An eyewitness said the car bomb was huge. Windows were shattered into pieces in most of the surrounding and nearby hotels.

Just a few hours after the car bombing, several rocket-propelled grenades hit several police stations and military checkpoints in various neighborhoods of Aden, according to an intelligence officer who did not give the number of casualties.

The attack was the latest in a string of bombings and killings targeting senior Yemeni military and security officers and some foreigners in the last few months.

No group has so far claimed responsibility for the attacks yet, but militants of the Yemen-based al-Qaida offshoot are often behind such attacks and assassination attempts, mostly in the country's southern regions.

Al-Qaida in the Arabian Peninsula, which emerged in January 2009, is considered the most strategic threat to the Yemeni government and its neighboring oil-rich Saudi Arabia.