Hours later, a suicide bomber blew himself up in front of an army patrol vehicle in the southern port city of Aden, wounding four soldiers, witnesses and a security official said.

In Lahej, Commander Amin Al-Shami’s car went up in flames from an apparent car bomb after he left an air base in Lahej province, witnesses said. A security source said two people riding in the vehicle survived the attack.

He also said police seized a bomb factory in the southern city of Aden and arrested one person.

“We are still looking for a number of suspects, including a Saudi. This is the group that blew up Al-Qawla police station (in Aden) on Saturday and tried to assassinate the defense minister in Aden last month,” the source said.

Aden, which lies east of a strategic shipping strait where some 3 million barrels of oil pass daily, has been in a security clampdown for months. Its neighboring province, Abyan, has been plunged into chaos since militants suspected of ties to Al-Qaeda began seizing cities in the coastal region several months ago.

President Ali Abdullah Saleh, in power for 33 tears, has been clinging to power even as protests paralyze swaths of the country and other areas are wracked with violence.

Witnesses who saw the suicide bomber in Aden on Tuesday said the assailant was a young man, and stepped out of a car to approach the army patrol. Only he died in the attack however.

“He pressed a mechanism inside his shirt and blew himself into pieces,” one resident said.

“The blast shook nearby homes and shattered windows.”

Aden has not only been rocked by repeated attacks on security targets, it is also the site of mass internal migration.

Tens of thousands of refugees have fled into the coastal city and neighboring provinces to escape the bloodshed in neighboring Abyan province, where the Yemeni army is still struggling to regain territory lost to the militants.

No suspects were immediately named for the attacks on Tuesday.

While Al-Qaeda has been blamed for most recent attacks, other suspects could be separatist militants.