Fifteen children among more than 300 dead after Somalia's deadliest bomb attack

Fifteen children are among the dead following Somalia's deadliest bomb attack, authorities have said, as the number of those killed rose to more than 300.

The director of an ambulance service in Mogadishu said the primary-age pupils were on a school bus near to where a truck bomb exploded at a busy intersection on Saturday .

It was the first of two blasts, with the second striking the city's Medina district two hours later.

More than 300 people have now been confirmed dead, and the number is expected to rise.

Abdikadir Abdirahman, director of Aamin ambulances, said: "The death toll will still be higher because some people are still missing."

Aamin, Mogadishu's only free ambulance service, tweeted pictures of the scene, saying: "In our 10-year experience as the first responder in Mogadishu, we haven't seen anything like this."

President Mohamed Abdullahi Mohamed has joined thousands of people in donating blood to help survivors as overwhelmed hospitals struggle to assist badly wounded victims.

Officials said more than 70 critically injured people were being airlifted to Turkey for treatment on Monday as international aid began to arrive.

The International Committee of the Red Cross says four volunteers with the Somali Red Crescent Society are among the dead, with "a number" of volunteers still missing.

A 50-year-old man who lived in Minnesota is also among the dead, according to reports in the US.

Ahmed AbdiKarin Eyow was in a hotel room when the bomb went off, the Minneapolis Star Tribune said.

Somalia is in three days of mourning following the blasts - the deadliest single attack the African country has ever experienced.

Mogadishu's mayor Tabid Abdi Mohamed has visited those wounded in the blast and said the horror of the attack was "unspeakable".

He said: "There is no tragedy worse than when someone comes to the dead body of their relative and cannot recognise them."

Michael Keating, the United Nations special envoy to Somalia, called the attack "revolting" and said the UN and African Union were supporting the Somali government's response with "logistical support, medical supplies and expertise".

Information minister Abdirahman Osman said other countries including Kenya and Ethiopia had already offered to send medical aid.

Somalia's government has blamed the attack on the al Shabaab extremist group, which has not commented.

Mogadishu is often a target for al Shabaab, which is allied to al Qaeda.