A car bomb exploded outside a police college in Yemen's capital Sanaa early on Wednesday, killing around 40 people and wounding more than 50 others, police sources and residents said.

Security in Yemen has diminished since a 2011 popular uprising that led to a change of government and splits in the army. Al Qaeda in the Arabian Peninsula (AQAP), one of the movement's most active wings, has staged a growing number of bombings and shootings across the country.

The victims from Wednesday's blast included students at the college and people waiting in line to enroll with the police, the police sources said, as well as passers by.

Ambulances were transporting casualties away from the scene of the blast, and bodies were seen lying in the street, witnesses said.

The explosion was heard across the city and a large plume of smoke was visible in the area of the college.

Photographs purporting to show the aftermath of the explosion, distributed on Twitter, showed the mangled wreckage of a vehicle and bloodied people lying prone on a pavement, but the pictures could not be immediately verified.

Western and Gulf Arab countries fear that further instability could weaken the country's government, giving AQAP more space to plot attacks outside Yemen's borders.

On Jan. 1 a suicide bomber killed at least 26 people at a cultural center in the central Yemeni city of Ibb in an attack that appeared to target the Houthi Shi'ite Muslim militia that seized the capital in September and advanced into other areas.

Most attacks in the past four years have targeted the country's security infrastructure. A suicide bomber killed more than 90 people in May 2012 at a military parade, and a coordinated assault on a military hospital a year ago killed more than 50.

Reuters-YOL