In Punjab curfew was imposed in parts of industrial town of Ludhiana city today as mob turned violent following clashes between two groups of migrant labourers in Dhandari area of the city last night and today. <br/> <br/>The mob turned violent after police allegedly did not register their complaints regarding theft by some unidentified persons last night. The mob which comprised labourers of other states, set ablaze vehicles on the Ludhiana-Ambala G T road and also resorted to heavy stone pelting, in which some policemen were also injured today. <br/>Police opened fire in the air and lobbed teargas shells to quell the violence before the authorities imposed curfew in five police station areas. Heavy police force has been deployed in the curfew bound areas. Ludhiana- Amabala highway have been closed at Dhandari and traffic has been diverted on alternative routes. The violent mob squatted on the Ludhiana- Delhi rail track, resulting in disruption of train traffic. Railway tracks which were jammed by protesters have been opened but railway authorities have stopped trains as a precautionary measures. No loss of railway property has been reported so far. Official sources said that the situation is tense but under control.<br/>