Story highlights Twin blasts rocked Mogadishu in October

No group has claimed responsibility for attack

(CNN) The number of dead in the devastating twin bombing in the Somali capital of Mogadishu in October has jumped to 512, authorities announced Sunday.

Nearly 70 people remain missing, and 295 still have injuries suffered in the attack, Abdullahi Mohamed Shirwac, the chairman of the 11-member government investigation committee, said in a press conference.

The October 14 attack was already the deadliest in Somalia's modern history. Government officials reported the death toll at 358 near the end of October. Two Americans were killed in the blast, the US State Department said.

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It was not immediately clear what caused the death toll to increase so significantly more than a month and a half after the deadly attack. There still has been no claim of responsibility.

The initial vehicle bomb destroyed dozens of stalls and the popular Safari Hotel in the heart of the city. Minutes later, a second vehicle bomb went off nearby.

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