A truck bomb exploded at a busy security checkpoint in Somalia's capital Saturday morning, killing at least 73 people, authorities said. It was one of the deadliest attacks in Mogadishu in recent memory, and witnesses said its force reminded them of the devastating 2017 bombing that killed hundreds of people.

The toll could rise as scores of people were rushed to hospitals, government spokesman Ismail Mukhtar told The Associated Press. Dr. Mohamed Yusuf, director of Madina hospital, said they had received 73 bodies. Abdiqadir Abdirahman, director of the Aamin Ambulance service, counted more than 50 wounded.

Most of those killed were university and other students returning to class, Mayor Omar Mohamud Mohamed said at the scene. Police said two Turkish nationals were dead.

Captain Mohamed Hussein said the blast targeted a tax collection center during the morning rush hour as Somalia returned to work after its weekend. A large black plume of smoke rose above the capital.

Images from the scene showed the mangled frames of vehicles and bodies lying on the ground. At a hospital, families and friends picked through dozens of bodies.

“I saw many dead bodies lying on the ground,' witness Mohamed Abdi Hakim said. “Some of those dead were police officers, but most of them were students.'

There was no immediate claim of responsibility for the blast. The al-Qaida-linked al-Shabab often carries out such attacks. The extremist group was pushed out of Mogadishu several years ago but continues to target high-profile areas such as checkpoints and hotels in the seaside city.

The extremist group is now able to make its own explosives, its “weapon of choice,” United Nations experts monitoring sanctions on Somalia said earlier this year. The group had previously relied on military-grade explosives captured during assaults on an African Union peacekeeping force.

Al-Shabab was blamed for the truck bombing in Mogadishu in October 2017 that killed more than 500 people. The group never claimed responsibility for the blast that led to widespread public outrage. Some analysts said al-Shabab didn't dare claim credit as its strategy of trying to sway public opinion by exposing government weakness had badly backfired.

“This explosion is similar like the one ... in 2017. This one occurred just a few steps away from where I am and it knocked me on the ground from its force. I have never seen such a explosion in my entire life,' said witness Abdurrahman Yusuf.

The latest attack again raises concern about the readiness of Somali forces to take over responsibility for the Horn of Africa country's security in the coming months from the AU force.

Al-Shabab, the target of a growing number of U.S. airstrikes since President Donald Trump took office, controls parts of Somalia's southern and central regions. It funds itself with a “taxation” system that experts describe as extortion of businesses and travelers that brings in millions of dollars a year.