At least 45 people were killed Monday in a suicide attack targeting army recruits in the southern Yemeni city of Aden, according to information from international medical charity Doctors without Borders (MSF) and a local security official.
The Islamic State extremist group claimed the attack, via its media outlet Aamaq Agency.
The blast happened when a suicide attacker driving an explosive-rigged vehicle blew himself up amid potential recruits gathering at a school in the city's Mansoura district, the security official said, speaking on condition of anonymity.
MSF's Yemen branch wrote on Twitter that its hospital in Aden - the city that serves as the temporary capital of Yemen's internationally recognized government - had received 45 dead and at least 60 wounded from the blast.
Islamic State supporters have claimed responsibility for similar attacks in May that killed 72 would-be army recruits in Mukalla and the southern port city of Aden.
The Yemeni branch of al-Qaeda has also claimed recent attacks on security forces in government-held southern Yemen.
The security official said that most of the recruits were from Abyan in southern Yemen, the home province of Saudi-backed President Abd Rabu Mansour Hadi.
Hadi's government has been seeking to recruit new troops in recent months for its struggle against the Houthi rebels, who control most of northern Yemen, including the capital Sana'a.
The mainly Shiite Houthis enjoy the backing of Yemen's most effective military forces, which remain loyal to former president Ali Abdullah Saleh.
Saleh's political party recently joined the Houthis in forming a new presidential council to rule the country, a move that drew a sharp rebuke from UN peace envoy Ismail Ould Cheikh Ahmed.
Fighters aligned to Hadi's government, backed by Gulf troops and Saudi-led airstrikes, drove the Houthis and their allies from Aden last year.
But the Saudi-backed government has been unable to ensure security in Aden and other areas it nominally controls, with al-Qaeda and Yemen's recently formed branch of Islamic State highly active.