A man apparently distraught over personal issues has driven his SUV into a crowd in Graz, Austria's second largest city, killing three people and injuring 34 others.

The governor of the Styria province, Hermann Schuetzenhoefer, gave the casualty figures and described the suspected driver as a 26-year old Austrian who was "mentally disoriented" and acting alone.

He said one of the injured is in a critical condition.

Police said the driver had been arrested. They said there were no indications of a terrorist attack, and the suspect was apparently distressed over personal problems when he targeted his victims.

About 60 ambulances converged on the scene and the Austrian auto club sent four helicopters to bring the victims to hospitals.

State broadcaster ORF cited unnamed witnesses as saying the man apparently drove his vehicle into the crowd at random, sending several people crashing into the windscreen and flying over the car.