Updated

The death toll from Saturday's truck bombing in Somalia's capital is now over 300, the director of an ambulance service said Monday, as this country reeled from the deadliest single attack it's ever experienced.

More people have died of their wounds in the past few hours, said Dr. Abdulkadir Adam of Aamin Ambulance. Funerals have continued and the death toll is expected to rise further.

Saturday's truck bombing targeted a crowded street in Mogadishu, and about 300 others were injured. Somalia's government is blaming the Al-Qaeda-linked al-Shabab extremist group, which has not commented.

More than 70 critically injured people were being airlifted to Turkey for treatment on Monday as international aid began to arrive, said officials. Nervous relatives stood on the tarmac at the airport, praying for the recovery of their loved ones.

Overwhelmed hospitals in Mogadishu were struggling to assist other badly wounded victims, many burned beyond recognition.

The attack was one of the worst in the world in recent years. It is one of the deadliest attacks in sub-Saharan Africa, larger than the Garissa University attack in Kenya in 2015, in which 148 died, and the U.S. Embassy bombings in Kenya and Tanzania in 1998, in which about 219 were killed.

In addition to Tukey, Kenya and Ethiopia have offered to send medical aid in response to what Somali's government has called a "national disaster," said Information Minister Abdirahman Osman.

Al-Shabab, Africa's deadliest Islamic extremist group, often targets high-profile areas of Mogadishu. Earlier this year, it vowed to step up attacks after both the Trump administration and Somalia's recently elected president announced new military efforts against the group.

The country's Somali-American leader, President Mohamed Abdullahi Mohamed, has declared three days of mourning and joined thousands of people who responded to a desperate plea by hospitals to donate blood.

"This is really horrendous, unlike any other time in the past," said Dr. Mohamed Yusuf, the director of Medina hospital.

Exhausted doctors struggled to keep their eyes open, while screams from victims and newly bereaved families echoed through the halls.

Mogadishu, a city long accustomed to deadly bombings by al-Shabab, was stunned by the force of Saturday's blast. The explosion shattered hopes of recovery in an impoverished country left fragile by decades of conflict, and it again raised doubts over the government's ability to secure the seaside city of more than 2 million people.

The United States has condemned the bombing, saying "such cowardly attacks reinvigorate the commitment of the United States to assist our Somali and African Union partners to combat the scourge of terrorism." It tweeted a photo of its charge d'affaires in Somalia donating blood. But the U.S. Africa Command said U.S. forces had not been asked to provide aid.

The U.S. military has stepped up drone strikes and other efforts this year against al-Shabab, which is also fighting the Somali military and over 20,000 African Union forces in the country.

Saturday's blast occurred two days after the head of the U.S. Africa Command was in Mogadishu to meet with Somalia's president, and two days after the country's defense minister and army chief resigned for undisclosed reasons.

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