Sanaa, Yemen (CNN) At least 38 people were killed and dozens others were injured in a car bomb explosion in front of the Police College in the Yemeni capital Sanaa Wednesday morning, two top Interior Ministry officials told CNN.

The bomber parked his vehicle in the middle of the road and then boarded another that was waiting for him, said AbdulBari Al Shamiri, a witness to the explosion.

"As soon as he left the scene, everyone 100 meters from the explosion was killed or injured," Al Shamiri said.

Police recruits were waiting in line at the gates of the Police College when the attack took place, the interior ministry said.

No group immediately claimed responsibility for the attack.