Mourners started burying the victims of twin bombings in the Somali capital of Mogadishu on Monday as the death toll rose to more than 300. It is the deadliest attack in the country’s history and one of the worst in the world in recent years.

About 300 other people were wounded in the attacks at busy junctions in a crowded shopping district Saturday. The Somali government blames on the al-Shabab extremist group, which vowed to step up attacks after the U.S. and Somalia’s new president announced new military action against it earlier this year.

Al-Shabab has not commented. Hundreds of residents marched in Mogadishu to protest against the militants.

Ambulance service director Abdulkadir Adam said more people died of their wounds Monday, as the death toll was expected to rise further, the Associated Press reported. Overwhelmed hospitals struggled to assist victims as thousands of people donated blood.

More than 70 critically injured people were being airlifted to Turkey for treatment, according to the AP. Information Minister Abdirahman Osman said countries including Kenya and Ethiopia had offered to send medical assistance.

President Mohamed Abdullahi Mohamed, known as Farmajo, called for three days of mourning.

"Terror won't win," he said in the capital after donating blood and visiting some of the wounded. "I call on our citizens to come out, extend help, donate blood and comfort the bereaved. Let’s get through this together."

A truck bomb exploded outside a hotel in the K5 intersection that is lined with government offices and restaurants, destroying buildings and setting dozens of vehicles ablaze, Reuters reported. Another bomb detonated in the Medina area two hours later.

Al-Shabab has carried out a series of attacks in recent years aimed at establishing a radical Islamist state.

“They don’t care about the lives of Somali people, mothers, fathers and children,” said Prime Minister Ali Khaire. “They have targeted the most populated area in Mogadishu, killing only civilians.”

The United States and Britain were among the countries to condemn the attack.

“We extend our‎ deepest condolences to all Somalis, especially those who lost friends and family in the attacks. We further wish for a quick recovery for all those injured," said Department of State spokesperson Heather Nauert in a statement.

“In the face of this senseless and cowardly act, the United States will continue to stand with the Somali government, its people, and our international allies to combat terrorism and support their efforts to achieve peace, security, and prosperity,” she added.

British Foreign Secretary Boris Johnson said: “My thoughts are with families of the victims, and the Government and people of Somalia at this difficult time.

“Those responsible have shown no regard for human life or the suffering of the Somali people. The UK will continue to support Somalia in the fight against terrorism."

"We pray that the Almighty Allah will grant the bereaved families & the people of Somalia the strength & courage to overcome this great loss," tweeted Kenyan President Uhuru Kenyatta.

Kenya has been the victim of al-Shabab attacks including an attack at the Garissa University in 2015 that killed about 150 people and an attack at the Westgate shopping mall in Nairobi in 2013 that killed around 70.

Contributing: John Bacon