The clash took place near Balmiki Chowk when Dera Sacha Sauda followers allegedly clashed with some Sikhs who were on their way back from a meeting in Gurdwara Dashmi Patshahi, police said.
The meeting was held to chalk out a strategy for seeking action against some Dera followers who had recently attacked few Sikhs near Rania in the district, they said.
The clash was in retaliation of the incident in which some Sikhs had allegedly showed black flags in Ellenabad to Dera Sacha Sauda chief Gurmeet Ram Rahim Singh while he was on way to Rajasthan a few days back, sources said.
Heavy police force has been deployed in the town to prevent any untoward incident.
According to sources, two jeeps were among the vehicles set on fire by the mob.
The incident led to tension in Sirsa, forcing the authorities to clamp curfew in Sirsa City this evening.
Dera Sacha Sauda is a religious sect based in Sirsa, where the situation was tense but under control, sources said.