CCTV footage captured the incident which occurred on July 19.
The explosion, which impacted five blocks, flipped vehicles and split the roadway, killing at least one person and injuring dozens.
Watch the shocking footage below.
City of Johannesburg officials confirmed on Friday the cause of the Lilian Ngoyi Street (formerly Bree Street) explosion in the CBD was caused by gas.
In a briefing on Friday, city manager Floyd Brink said technicians on the scene had uncovered an old gas line, believed to be an old Johannesburg Gas line.
The city has reportedly placed an emergency call for engineers and gas-detection experts to fix the gas issue and repair the road.
“WE DEFINITELY NEED ANY STRUCTURAL ENGINEERS, CIVIL ENGINEERS, ELECTRICAL ENGINEERS OR WATER ENGINEERS/GAS DETECTION EXPERTS. The City COO has undertaken that they will be paid and will conclude contracts within the hour,” said the message circulated by WhatsApp on Thursday.