The crash happened close to the Mount Pleasant Hotel on Great North Road shortly after midnight.
South Yorkshire Police said at around 12.25am, a Fiat Scudo minibus taxi and an LTI London taxi that were travelling in opposite directions along Great North Road collided close to the Mount Pleasant Hotel on Great North Road.
Two women in their 50s, who were in the LTI taxi, have died.
The victims were aged 59 and 52.
Two male passengers, also in their 50s and travelling in the same vehicle, suffered minor injuries, as did the 61-year-old driver.
The other taxi contained a 40-year-old driver and six passengers, three men aged 22, 25 and 29, and three women, aged 21, 25 and 26.
The six passengers in the Fiat and the driver all sustained minor injuries.
All of those involved in the collision were taken to hospital.
Yorkshire Ambulance Service sent eight ambulances, a rapid response vehicle and a hazardous area response team to the crash, with East Midlands Ambulance Service sending another ambulance and rapid response vehicle as well.
A spokesman for the ambulance service said earlier today three of the most-seriously injured casualties were taken to the Northern General Hospital in Sheffield, with others taken to Doncaster Royal Infirmary.
South Yorkshire Fire and Rescue Service were also required at the scene to help cut out two of the injured people who were trapped in one of the taxis.
An investigation into the cause of the crash has now been launched by South Yorkshire Police.
A spokesman for South Yorkshire Police said: “Anyone who may have seen the incident or witnessed the manner of driving of either vehicle before the collision, is asked to call 101 quoting incident number 26 of 31 January 2016.”