"This religious fighting has come as a shock to the city, as the area is multi-cultural and lives normally go on on here without violence.
"The full details of the attack are unclear as most of the injured were severely wounded and have been unable to talk to police."
He said there was speculation that feuding broke out after one group tried to gain worshippers from another temple.
Witnesses said a group of men had attacked two spiritual leaders, or gurus, who had travelled from India for the ceremony, and their followers had moved to defend them.
One of the gurus died and one was wounded.
A police spokeswoman said six suspects, of whom four were wounded and in serious condition, had been arrested.
The possibility that not only the attackers but also some of the worshippers were armed was being investigated.
In India, fighting between mainstream Sikhs and followers of the killed guru
broke out in the northern city of Jalandhar in what locals described as a reaction to the clash in Vienna.
Rioters reportedly pelted buses with stones and set a bus, lorries and shops ablaze.
The Sikh community has about 2,800 followers in Austria.
About 25 million people observe the Sikh faith worldwide, most of them in northern India.