Al Qaeda's North African affiliate is believed to be the culprit.
Via The New York Times :
Twin car bombs exploded in quick succession in the Algerian capital today, targeting United Nations offices and an Algerian government building, with news agencies reporting at least 67 people killed. One official said it was the worst day of violence in the country this decade.
The death toll may rise as the paper reports a dozen UN employees are still missing, assumed to be buried underneath the building's rubble.
According to BBC.com , the first car bomb destroyed a bus packed with students, while the second car bomb took aim at UN offices in the Hydra neighborhood of the capital city. The United Nations Development Programme building received the brunt of the blast. Algerian Interior Minister Yazid Zerhouni said the bombing against the UNDP building was the work of a suicide bomber.
Both the Times and BBC.com say the bombings were likely perpetrated by al Qaeda in the Islamic Maghreb, the terrorist group's North African affiliate. The group last attacked Algiers in April, killing 33 people in a triple-suicide bombing.
For more on al Qaeda in the Islamic Maghreb, see "A New Threat Rises in the Maghreb" in the July print issue of Security Management.