"There is smoke all over and paramedics are on the scene".
Emer-G-Med Chief Operating Officer Jurgen Kotze said the four critically injured patients were still entrapped in the aircraft.
The aircraft, a Convair 340 (ZS-BRV) was taking off from Wonderboom airport.
'We have 19 injured casualties ranging from minor to critical injuries at this stage and no confirmed fatalities'.
The large plane appeared to have crashed through a nearby building, the official said.
Aviodrome wrote on Facebook that it was "hugely shocked", by the crash.
"We suspect that the plane was on its way to the Wonderboom airport", said Mahamba.
The plane had been due to fly later this week to Aviodrome via east Africa, through Egypt, Croatia, Austria to the Netherlands.
"A statement with further details will be issued tomorrow", said Kabelo Ledwaba, spokesperson of the South African Civil Aviation Authority.
"ER24 paramedics, along with several other services, are now on the scene treating and triaging the patients", the emergency services group said in a statement on Tuesday.
The plane had the words "Martin's Air Charter" painted on it, which was a previous name of Dutch cargo airline Martinair.