A man, believed to be a 26-year-old Austrian, has now been arrested in relation to the incident.
Police have sealed off the downtown area of Graz, Austria, where the incident occurred at around midday local time (11 BST). Police confirmed the incident but would not release any details or confirm the number of dead or injured.
Ten of the 34 injured are believed to be in a “serious” condition, according to reports. Dr Sea Rottman told Sky News she was “lucky” to have missed the horrific incident by just “five minutes”.
She said: “I had a friend there and she said that she saw bodies flying through the air – it was absolute chaos and mayhem. “It has died down a little bit now in the last hour, but before that [the sound of emergency services] was pretty much constant.”
Around 60 ambulances arrived on the scene and four helicopters were sent to bring helicopters from the scene. Dr Rottman said she feared the incident was “deliberate”.
She added: “It looks like the driver was doing between 130kph and 140kph on a street he should not have been on in the first place.”
Provincial governor Hermann Schuetzenhoefer, who gave the casualty figures, described the suspected driver as a 26-year old Austrian.
According to reports, a seven-year-old is feared to be one of those killed in the incident which is believed not to be terror-related.
Mr Schutzenhofer told reporters a fourth person is fighting for their life. He called the man “deranged”, adding: “There is no explanation, there is no excuse.”
One newspaper – Kleine Zeitung – reported the man with Bosnian heritage was thought to be suffering with family problems. The unnamed man was said to have got out the car after ploughing into a pedestrians and launched a knife attack.
Mayor Siegfried Nagl ordered black flags of mourning to be flown from municipal buildings and cancelled street fests and other city events.