The heads of Somalia’s Olympic committee and football association are among seven people killed in a suspected suicide blast in Mogadishu.
The Somali Prime Minister, Abdiweli Mohamed Ali, was also present when the attacker struck, but he has told the BBC he was unhurt.
He blamed al-Shabab militants.
The theatre closed in the early 1990s as Somalia descended into civil war and was only reopened last month, amid a new period of relative optimism.
The President of the Somali Olympic Committee, Aden Yabarow Wiish, and the Somali Football Federation chief, Said Mohamed Nur, were among a group of dignitaries who had gathered to mark the first anniversary of the launch of Somalia’s national television station.
Sources have told the BBC Somali Service that three Somali television journalists were also wounded in the blast.
Al-Shabab militants who had controlled large parts of the country, including Mogadishu, were pushed out of the city by troops from the African Union last year.
Since then, there has been a period of relative quiet, with sporting activity resuming, restaurants opening, and the re-opening of the National Theatre.
But al-Shabab has continued to attack the capital with bombs and mortars.