ER24 spokesman Russel Meiring said that ER24 paramedics‚ along with several other services‚ were now on the scene treating and triaging the injured.
"Seen on Sunday morning at Pretoria's Wonderboom Airport‚ ex Rovos Air Convair 340 ZS-BRV‚" the caption read.
He said: "Initial reports show that approximately 20 people had sustained injuries ranging from minor to critical".
Paramedics helped survivors out of the aircraft and treated patients at the scene as firefighters tackled the smoking wreckage.More news: Saved Thai Soccer Team Can't Accept Invite to Attend World Cup Final
"We are unsure as yet of how the incident occurred".
A plane has crashed near the Wonderboom airport in Pretoria, South Africa.
Tshwane Metro Police Department spokesman Superintendent Isaac Mahamba said a small plane crashed in the Kameeldrift plot.
Paramedic Xander Loubser from BestCare Ambulance Service said: "There are critical patients".More news: Trump's longtime driver sues for thousands of hours of unpaid overtime
The plane had been due to fly later this week to Aviodrome via east Africa, through Egypt, Croatia, Austria to the Netherlands.
The plane hit a factory on Tuesday afternoon, critically injuring four workers before crashing.
The plane was marked Martin's Air Charter, but no information was immediately available about the air company. It had just been refurbished for 350,000 euros ($410,000) at Wonderboom.
Pieterse says Civil Aviation Authority will be investigating the crash.More news: Bishops call for 3-day fast after Duterte called God stupid