The international community is expressing outrage after a truck bomb in Somalia's capital, Mogadishu, tore through a government compound, killing at least 70 people and wounding dozens more.

United Nations Secretary-General Ban Ki-moon said Tuesday he is “appalled” by what he called the “vicious” attack. He said it is “incomprehensible that innocents are being senselessly targeted.” And he said the attack was even more “abhorrent” for happening when Somali political leaders have been working together for a peaceful future.

The insurgent group al-Shabab claimed responsibility for the attack, saying it was aimed at Somalia's Transitional Federal Government and African Union peacekeepers who assist the TFG.

The U.N. Security Council condemned the suicide bombing, and reaffirmed its support for the TFG, saying terrorism in all forms is “criminal and unjustifiable.”

The United States condemned what it called al-Shabab's “complete disregard for human life,” while Britain called the attack “callous” and France called it “vile.”

Many of the victims were students, who came to the Ministry of Education to learn the results of exams they took to obtain scholarships in Turkey.

The Somali government said the attack, al-Shabab's single deadliest strike since the beginning of its insurgency, shows that the danger from terrorists is not over.

Witnesses told VOA two suicide bombers drove a large truck up to the compound's entrance and detonated the bomb at mid-morning Tuesday.

Al-Shabab pulled its fighters from Mogadishu in August, but said it would continue to fight the government. The group is trying to seize power and to impose a strict form of Sharia, or Islamic law, across Somalia.

Al-Shabab has carried out suicide bombings with devastating effect in the past. In late 2009, a suicide bomber killed 24 at a graduation ceremony in Mogadishu.

Last July, twin bombings in Uganda's capital, Kampala, killed at least 76. Uganda contributes troops to the AU peacekeeping force in Somalia.