A military intelligence officer was killed by unknown gunmen in Yemen's southern province of Lahj on Saturday, local police said. Colonel Bassel Mohammed was killed in a drive-by shooting by armed men using silenced weapons near a public market in Lahj province, the police source told Xinhua on condition of anonymity. "The attackers arrived on a motorcycle and opened fire on the intelligence colonel outside Lahj's market, killing him on the spot," a local government official told Xinhua. Yemeni security forces have sealed off the scene and launched an investigation into the incident, the source said. On Thursday, unidentified gunmen opened fire at Colonel Mohamed al-Kodeemy, the assistant director of the Intelligence Bureau in neighboring southern port city of Aden. No group has so far claimed responsibility for the drive-by shooting, however, the militants of the Yemen-based al-Qaida offshoot were blamed for a series of assassination attacks, mostly in the country's southern regions. The al-Qaida in the Arabian Peninsula, which emerged in January 2009, is considered as the most strategic threat to the Yemeni government and neighboring oil-rich Saudi Arabia.