An Afghan man has been arrested after four people were injured in two knife attacks in Vienna, Austria.

Three pedestrians were attacked at random by a man wielding a knife near the capital's famous Prater Park at around 7.45pm local time.

Police say that the three victims hurt in the stabbing frenzy were a family, including a father, mother and their daughter, 17.

Then 30 minutes later, another person was seriously injured in a separate attack at Praterstern. A police spokesman confirmed all the victims were Austrian.

One eyewitness said the attack happened in front of a Japanese restaurant near the U1 Nestroyplatz station on the Praterstrasse. He claimed the male victim injured in the first attack suffered from a heart attack and that the attacker shouted 'Allah, Allah'. This has not been confirmed by police.

A heavy police presence is at the scene where at least three people have been stabbed in Vienna

The attack took place near the U1 Nestroyplatz station on the Praterstrasse, a busy road which runs directly from the city centre to the Praterstern transport hub

A police spokesman said: 'A man attacked a family - a father, a mother and their 17-year-old daughter - with a knife. The three people were seriously injured and their lives are in danger.

'And half an hour later, there was another attack ... at Praterstern and here a person was also seriously injured and their life is in danger. We do not know to what extent there is a connection here and any motive remains unclear.'

A male citizen of Afghanistan was later arrested in connection with the second assault, but no further details were immediately available and any connection between the stabbings remained unclear, the spokesman said shortly afterward.

It is unclear whether the man arrested is in any way connected to the first attack.

Eight emergency service vehicles were present at the scene and the U1 subway line was temporarily halted between 8.15pm and 8.45pm, although service has now resumed.

Pictures from the scene of the first attack shows a puddle of blood in the middle of the road alongside bits of rubbish. It has now been cordoned off by police as they search for clues.

Heavily armed police officers are now guarding the doors of buildings close to the scene, according to Heute.at. Locals have been advised to stay indoors.

Eight emergency service vehicles were present at the scene and the U1 subway line was temporarily halted between 8.15pm and 8.45pm

A manhunt is underway after several people were injured in a knife attack in Vienna, Austria