Shots were fired, stones thrown as violence broke out between party cadres of the opposition Sikkim Democratic Front and the ruling Sikkim Krantikari Morcha in Soreng, prompting the authorities to sound an alert on Saturday, said police sources.
An accused has been arrested and is in Soreng Police Station, said sources.
Reports say the violence started with a minor altercation over allowing a vehicle to pass.
Bullet shells, a gun holder were recovered from the scene of violence, said the police. Videos showed a person with a bloodied face.
Various places in west and south Sikkim have been put on alert after the firing incident, the sources added.
The police have appealed for calm.