SANAA - A Qaeda suicide bomber blew himself up at the entrance of a police academy in Sanaa on Wednesday, killing at least six cadets and wounding several more, the High Security Commission said."Terrorists from the Qaeda network" perpetrated this "cowardly attack, which killed eight students and wounded 20, some of them gravely," a commission statement said.Initially, 20 people were reported killed, but the official in charge of the investigation later said that, "after the victims were transferred, it became clear that the attack killed six people, and wounded dozens of others."However, he added that the toll "could rise as several of the wounded were in critical condition." Dozens of ambulances rushed to the scene to evacuate the casualties, witnesses said, adding that the blast took place at a seldom used southern entrance of the academy.At least 4,000 cadets study at the police academy in Sanaa, and witnesses said hundreds of them were leaving from the southern gate to head home for the weekend. Another security official, speaking on condition of anonymity, said the bomber detonated his explosives after "arriving in a vehicle" at one of the academy's entrances.One witness said the bomber had arrived in a taxi, which was "blown to pieces in the blast."There was no immediate claim of responsibility, but the commission named the attacker as Mohammed Ali Nasher al-Ari, and said he died on the way to hospital after losing several limbs in the explosion.A security official told AFP that 11 people were arrested shortly after the attack.An official also said that security had been beefed up around key government installations as well as embassies.Wednesday's blast is the second deadliest in the capital since President Abdrabuh Mansur Hadi took power in February pledging to destroy Qaeda's presence in the country.The police academy is located near Sabeen Square where a Yemeni soldier, packing powerful explosives under his uniform, blew himself up in the middle of an army battalion on May 21.Qaeda claimed it was behind that attack that killed more than 100 troops and wounded more than 300 others.On June 23, Yemeni troops seized Qaeda's last bastion in the country's troubled southern and eastern provinces after a month-long offensive aimed at ousting the jihadists from territory they had controlled for about a year.Taking advantage of a central government weakened by an Arab Spring-inspired uprising last year, the militants had overrun most of Yemen's southern Abyan province, capturing its capital Zinjibar, towns like Jaar, Shuqra and several other villages.Since their defeat, however, Qaeda has pledged to seek revenge. Late last month, an Qaeda suicide bomber killed Yemen's army commander for the south, General Salem Ali Qoton, who had led the offensive against the militants.Two other senior Yemeni security officials have been targeted for assassination since.On July 4, a Yemeni police chief in Sanaa narrowly escaped an attempt on his life when explosives planted in his car blew up just minutes after he exited the vehicle.Days earlier, intelligence officer Mohammed al-Qudami was killed by a bomb planted under the seat of his car.No one claimed responsibility for the blasts but officials have said that the attacks bear the hallmark of Qaeda.The militants have also left mines in the cities and towns they fled that have so far claimed the lives of dozens.