Police in Austria are searching for an armed man who killed an ambulance driver and three police officers before barricading himself in a farm building.

After a 12-hour standoff, police on Tuesday stormed the building on the outskirts of Melk, 70km west of Vienna, but had not found the man, Interior Ministry spokesman Karl-Heinz Grundbock said.

The killings began shortly after midnight on Monday when police stopped the man on a road near a wilderness area west of Vienna, where frequent poaching incidents occur.

The gunman fled in his car, before crashing it into a ditch in the nearby town of Annaberg. He then shot and wounded a member of Cobra armed police team at a police checkpoint.

The gunman then shot and killed an ambulance driver who was trying to aid the wounded policeman, who later died. The gunman also shot and wounded another officer at the scene. 

He then shot and killed another police officer while stealing his patrol car. The vehicle and the officer's body were found on Tuesday.

The attacker then fatally shot another police officer at a roadblock before barricading himself in the farm building.

State broadcaster ORF reported that the suspect was a 55-year-old poacher. Police identified him only as Alois H, in keeping with Austrian law allows suspects anonymity.

Source: Agencies