A suicide bomber reportedly killed at least 90 people in an attack carried out during rehearsals for a military parade in the Yemeni capital, Sanaa, Monday morning.

The bomber targeted soldiers practicing for an army review to commemorate Yemen’s national day on Tuesday, which Yemeni president Abd al-Rab Mansur al-Hadi is scheduled to attend, Reuters reported.

According to the BBC, the bomber, clad in a military uniform, detonated his bomb as the soldiers marched through Sabin Square, near the presidential palace.

In Sanaa, no one immediately claimed responsibility for Monday’s suicide bombing, but the soldiers targeted were mostly troops from Yemen’s Central Security, a paramilitary force commanded by Yahya Saleh, a nephew of ousted president, Ali Abdullah Saleh.

Saleh stepped down in February as part of a U.S.-backed power-transfer deal brokered by Gulf Arab countries. It gave Saleh immunity from prosecution in return for relinquishing his power.

Yemeni troops have been battling al-Qaeda militants for months. On Sunday, 17 people were killed in clashes as the army pushed on with an offensive to regain a key town in the county’s south that fell to al-Qaeda more than a year ago.

Also Sunday, militants opened fire on U.S. Coast Guard trainers in the port city of Hodeida, wounding one.