Riots have broken out in almost all towns and cities in the Indian state of Punjab after a Sikh guru was killed by a rival group in a temple in Austria.

Thousands of angry protesters have taken to streets, damaging public property and setting trains on fire, the BBC reported Monday.

At least four people were injured when police opened fire at protesters who attacked a police station in Jalandhar.

The army has marched through the streets of Jalandhar city and a curfew is in place in four major towns.

Indian Prime Minister Manmohan Singh has appealed for calm.

Guru Sant Ramanand was attacked on Sunday in Vienna - during clashes at a religious ceremony - by six men armed with knives and a pistol.

He succumbed to his wounds in hospital early Monday.

Another preacher Sant Nirajnan Das, who was among 15 other people injured, is said to be stable.

Both the preachers were from a low-caste Sikh sect which has a large following in parts of Punjab and had travelled to Vienna to conduct a special service.