People gather in front of the gates of the police academy in Sana'a where a suicide bomb attack took place, Wednesday. — ReutersSANA'A — At least 22 people were killed in a suicide bombing at a police academy in the Yemeni capital Sanaa on Wednesday, an attack police investigators said bore the hallmarks of Al-Qaeda. Medics said dozens of people were also injured in the attack, which appeared to have been timed to coincide with the cadets leaving the academy at the end of the school day. Witnesses said police closed the scene of the attack and began investigating the blast as ambulances ferried casualties to hospital. The attack appeared to mirror a suicide bombing in May, when a suicide bomber in army uniform struck at the heart of Yemen's military establishment, killing more than 90 people during a rehearsal for an army parade in Sanaa. That attack was claimed by Al-Qaeda in the Arabian Peninsula (AQAP), which US officials have described as the most dangerous grouping of the global militant network. Islamist militants 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. After becoming president, Hadi said one of his most important tasks was the continuation of the war on Al-Qaeda and he instructed the military to regain control of several key towns in the southern province of Abyan. Last month, the army recaptured the provincial capital, Zinjibar, after a campaign which left hundreds of militants and dozens of soldiers dead. In a separate development, the government announced that it had arrested two of the five Al-Qaeda militants who had tunnelled out of a prison in the western province of Hodeida last month. One of the two men, Nasser Ismail Ahmed Muttahar, was suspected of taking part in an attack on the US embassy in Sanaa in 2008, in which 19 people were killed, including an American woman. —Agencies