Two civilians died on Thursday when a shell hit their house in the al-Hassaba district of the capital, Sanaa, a source in the office of Sheikh Sadiq al-Ahmar, a tribal chief, said.

Mohammad al-Qadhi, a former managing editor of Yemen Times, told Al Jazeera that clashes had taken place between fighters supporting Sadiq, the leader of the most powerful tribal federation, and troops loyal to President Ali Abdullah Saleh.

Al-Ahmar is among the tribal leaders calling for the departure of President Ali Abdullah Saleh. Two of his fighters were wounded in the shelling, the source said.

Elsewhere in Yemen,  a 14-year-old boy was killed on Thursday and five other people were wounded during an exchange of fire that followed two blasts near a police station in the port city of Aden.