At least 10 people were killed in a large explosion, believed to be a suicide bombing, at the Yemeni police academy in the capital Sana'a, medics and a police source said.
The police source said the blast took place as cadets were leaving the academy as classes finished.
Medics at the scene said dozens more were wounded in the explosion at the entrance to the police academy.
In May, a suicide bomber in army uniform struck at the heart of Yemen's military establishment, killing more than 90 peopleduring a rehearsal for an army parade in the capital Sana'a.
The attack was claimed by al Qaeda in the Arabian Peninsula (AQAP), which US officials have described as the most dangerous franchise of the global militant network.
Fighters linked to al Qaeda have vowed to carry their fight across Yemen after a US-backed military offensive in May drove them out of strongholds they took last year during protests against former President Ali Abdullah Saleh's rule.
A number of attacks since the recent offensive indicate that the militants still pose a serious threat.