(CNN) -- The death toll rose to 23 on Friday in a suicide bombing attack at a Somali graduation ceremony, which killed three members of Somalia's U.N.-backed interim government, according to an independent media report.
The attack in Mogadishu on Thursday was carried out by a male suicide bomber dressed in women's clothing, witnesses said.
Government officials said Thursday that 19 people had been killed in the attack. A day later, Shabelle Media reported that the death toll had risen to 23.
Somali President Sheikh Sharif Sheikh Ahmed has blamed the Islamist rebel group Al-Shabaab for the attack. A spokesman for the militant group denied any responsibility Friday.
Education Minister Abdullahi Wayel, Health Minister Qamar Aden and Higher Education Minister Ibrahim Hassan Adow were among the dead in the bombing at Banadir University's commencement, officials said.
Sports Minister Suleman Olad Roble was hospitalized in critical condition, his relatives told local media. The fatalities included nine students and two doctors, according to a professor at the university. Journalists said three colleagues died in the blast.
Al Shabaab is made up of former allies of Ahmed, once a leader of the Islamist movement that briefly held power in Mogadishu in 2006.
Ahmed and other former members accepted a U.N.-brokered peace agreement with the government they once fought. Al-Shabaab -- which the United States says has links to al Qaeda -- has rejected the peace agreement and has waged a bloody campaign against the transitional government.
CNN's Ben Brumfield and journalist Mohamed Amiin Adow contributed to this report.