The al-Hasaba district in the capital Sana'a was tense overnight Thursday with arriving military reinforcements, following a truce of more than a month in the neighbourhood, which was the scene of significant fighting during Yemen's unrest, DPA reported.
Residents of the area heard several explosions late Thursday, and some roads into the area were blocked by gunmen believed to be supporters of tribal leader Sheikh Sadiq al-Ahmar.
In May, confrontations between government forces and armed al-Ahmar tribesmen left some 300 people dead on both sides, with more than 1,000 wounded.
Protests have continued for six months in Yemen against President Ali Abdullah Saleh.
Sana'a and other provinces have suffered power outages for up to 23 hours a day. The blackouts are seen by many people as collective punishment for the revolt against the regime.