A military vehicle belonging to the presidential guards, which was seized by Houthi fighters during clashes, is seen outside the Presidential Palace in Sanaa, January 21, 2015.

An explosives expert inspects the damage at the scene of an explosion in Sanaa, January 22, 2015. An improvised explosive device was detonated under the car of a National Security officer in Sanaa on Thursday causing damage to it without casualties, police officials said.

Members of the Shiite Huthi movement inspect a damaged mosque following clashes the previous day between Huthi militiamen and the presidential guard in the capital Sanaa, January 20, 2015.

Houthi fighters stand near a damaged guard post at a Presidential Guards barracks they took over on a mountain overlooking the Presidential Palace in Sanaa, January 20, 2015.

Yemeni President Abed Rabbo Mansour Hadi shakes hands with friends and family members of Major General Salem Ali Qatan, the slain commander of military forces in the south of Yemen, in Sanaa, June 19, 2012.

A Yemeni man walks amid the debris inside a heavily damaged house near the presidential palace in Sanaa, January 20, 2015.

Houthi fighters take up position on a street during clashes near the Presidential Palace in Sanaa, January 19, 2015.

Members of the Shiite Huthi movement inspect a damaged mosque, January 20, 2015.

Yemeni men walk past a damaged building on January 20, 2015, following clashes the previous day between Huthi militiamen and the presidential guard near the presidential palace in the capital Sanaa.

A tank is positioned next to home of Yemeni President Abdrabuh Mansur Hadi in the capital, Sanaa, on January 21, 2015.

A member of the Shiite Huthi movement mans a checkpoint near the presidential palace in the capital, Sanaa, on January 21, 2015 after they seized control of Yemen's presidential palace and attacked President Abdrabuh Mansur Hadi's residence.

The Huthis want changes to a draft constitution opposed by the militia.

A member of the Shiite Huthi movement mans a checkpoint near the presidential palace in the capital, Sanaa, on January 21, 2015.

A Shiite Huthi militiaman wearing uniform confiscated from the Yemeni army stands on a government tank in the area around the house of the country's president in the capital Sanaa, January 22, 2015.

Shiite Huthi militiamen wearing uniforms confiscated from the Yemeni army stand at a barrier in the area around the house of the country's president in the capital Sanaa, on January 22, 2015.

People walk past a burned van following Monday's clashes between Houthi fighters and Presidential Guard troops near the Presidential Palace in Sanaa, January 20, 2015.

Houthi fighters ride a truck while patrolling a street in Sanaa, January 21, 2015.

Houthi fighters ride a truck near the presidential palace in Sanaa, January 22, 2015.