Three police officers and an emergency worker have been shot dead while trying to arrest a suspected poacher, the Austrian interior ministry has said.
Police armed with machine-guns are surrounding a farmhouse near the Alpine ski resort of Annaberg, where the suspect has barricaded himself in.
The man is heavily armed, reported state broadcaster ORF quoting police.
The suspect had been arrested during the night but escaped in a stolen police car, fleeing to his house.
Around 100 special forces officers are surrounding the property in the village of Melk, about 90km (55 miles) west of the capital Vienna, ORF reported.
Sporadic shots have been fired at officers, who have described the situation as “terrible and very explosive”.
Police have so far failed to make contact with the gunman, ORF reported, adding that relatives of the suspect have been brought in to help.
Police tried to apprehend the suspect late on Monday after receiving information that he had been hunting illegally.
However, the man – said to be in his mid-50s – reportedly opened fire after driving into a ditch, injuring a police officer who later died in hospital.
A paramedic was shot dead as he tried to help the officer, and a second policeman was injured, reports said.
The gunman then fled on foot, killing a second police officer and taking a third hostage.
He stole their police car and drove, with his captive, some 60km to his farmhouse.
Officials later reported that they had discovered the body of the third policeman at the farm.
A large section of the surrounding area has been cordoned off, with police in body armour and carrying machine-guns manning road-blocks.
Armoured police vehicles have also been deployed.
An earlier information blackout was lifted after information was leaked by the media. (BBC)