A suspected poacher has shot dead three policemen and a paramedic in Austria, then barricaded himself in his farmhouse and opened fire on special forces outside.

The man first shot two policemen as they tried to arrest him in woodland in the province of Lower Austria near Vienna.

He also killed a paramedic who was treating a wounded officer at the scene

The force said the man then fled in a stolen police car to his home near the city of Melk, about 70km away, taking a third policeman with him as a hostage.

That officer was later found dead in the car, the Austria Press Agency reported, though the force was not immediately available to confirm the report.

Dozens of Cobra special forces were surrounding the building where the man had opened fire, the police spokesman said.

"The gunman keeps shooting at the Cobra forces ... The Cobra forces are working very slowly and carefully," he told Reuters.

Reuters journalists kept at a distance from the scene saw a hearse and three armoured personnel carriers driving towards the farm.

Violent crime is rare in Austria but hunting is a centuries-old tradition in the Alpine republic enjoyed by tens of thousands, many of them farmers and landowners.