SANAA (AP) ― A suspected al-Qaida suicide bomber detonated his explosives among a crowd of Yemeni police cadets as they were leaving their academy Wednesday, killing at least 10 of them, according to security officials.

The Interior Ministry said al-Qaida was behind the bombing, which struck in the capital Sanaa. Security officials said 20 cadets were wounded, including three critically. They were leaving the Police Academy for a weekend with families when the bomber hit at the facility’s southern gate.

The Interior Ministry identified the attacker as Mohamed Nasher al-Uthy from the province of Amran, about 70 kilometers northwest of Sanaa. It said he lost the lower part of his body in the blast and died of his wounds minutes later. No other details were provided.

Twelve suspects were arrested in connection with the bombing, according to security officials. There was no immediate claim of responsibility, but al-Qaida’s branch in the impoverished nation on the southern tip of the Arabian peninsula frequently targets security forces.

The capital was on high alert after the attack, with security forces setting up checkpoints around the city and searching cars. Security was also beefed up around embassies.

The attack came after the army last month recaptured several militant-held towns in the country’s south, following a months-long campaign to retake territory the militants seized during last year’s political turmoil that swept the country in the wake of an Arab Spring uprising.

Al-Qaida in the Arabian Peninsula, considered the global terror movement’s most dangerous offshoot, has struck back against the military’s offensive with deadly attacks in the south and a May 21 bombing at a parade ground in Sanaa that killed 96 Yemeni soldiers.

Security officials said 55 people have been arrested in connection with that attack, among them al-Qaida militants accused of plotting to attack the U.S. Embassy.

Last week, Yemeni state TV aired several purported confessions of the detainees, with one of the accused saying he had orders to carry out an attack against the U.S. Embassy and other foreign embassies. He did not elaborate.

Earlier Wednesday, the government announced that two al-Qaida militants who tunneled out of a prison last month were re-arrested in a southern province. The Interior Ministry said one of the two, Nasser Ismail Ahmed Muttahar, was detained for taking part in an attack on the U.S. Embassy in Sanaa in 2008.

That attack on the embassy’s gate, carried out by gunmen and vehicles packed with explosives, killed 19 people, including an 18-year-old American woman and six militants. None of those killed or wounded were U.S. diplomats or embassy employees. It was the deadliest assault on a U.S. embassy in a decade.

The two militants who had escaped prison were captured in al-Dhali province on Tuesday. The ministry said they were among five militants who escaped from a prison in the western province of Hodeida on June 26.

In another of Yemen’s multiple ongoing conflicts, the army shot dead a protester Wednesday in the southern port city of Aden and wounded four others, including two women, a security official said.

He said the demonstrators were protesting the government’s decision to deploy army units inside Aden. What started as a peaceful demonstration turned violent as marchers started throwing rocks at the army, which then opened fire to disperse them.

Aden, the capital of a separate country before it unified with the north in 1990, is experiencing a wave of protests calling for the secession of the south.