Curfew was imposed in Dhubri town of Assam on Wednesday after six persons were injured in two rounds of clashes between police and protesters. Durga Puja celebrations were marred when police fired in airfor the second time in the dayto disperse people who gathered at a pandal violating the curfew. The curfew was imposed in the evening after protesters representing puja committees and police clashed following the stabbing of a pandal decorator late Tuesday.