At least 73 people were killed and 170 others injured on Wednesday when multiple explosions ripped through an area where a ceremony was being held to commemorate a top Iranian general who was assassinated four years ago by the US, the country’s National Medical Services Organization said, Azernews reports, citing Anadolu Agency.

The explosions took place on a route leading to the cemetery in the southeastern city of Kerman where Qassem Soleimani, the former head of the Islamic Revolutionary Guard Corps’ Quds Force, was laid to rest, according to state media.

The cause of the explosions remains unknown. Some media reports suggested that they were caused by gas canisters.

The incident happened as tens of thousands of people converged in Soleimani’s hometown Kerman to commemorate the fourth anniversary of his assassination.

Soleimani was killed on Jan 3, 2020, in a US drone strike outside Baghdad Airport in Iraq.

Officials of the Red Crescent Society in Kerman were quoted as saying by the state media that they took at least 50 people from the site of the incident to various hospitals.

Iran’s emergency services put all hospitals and health care centers on alert to attend to the injured.

Officials in Tehran have not commented on the incident yet.

According to Anadolu sources, the venue of the ceremony in Kerman has been vacated by security forces and people have been asked to return home.