Kolkata: Nobel laureate Amartya Sen on Monday said there is a "reason to worry" over the communal violence that has engulfed pockets in Basirhat sub-division of West Bengal's North 24 Parganas district."Why is it happening? Is it because someone is inciting it? We are all worried. How much political mischief is to be blamed for this? We have to ponder all these. There is a reason to worry over this," Sen told a television channel here when asked about it."Bengal has a culture of co-existence of Hindu-Muslim communities and for a long time this co-existence was possible without any communalism, and suddenly this returns. We can't be dismayed over this and let this be, thinking there is nothing to do in this matter... We have to take measures to get rid of these things," he said.The celebrated economist is in the city to attend the screening of a documentary on him directed by Suman Ghosh.Violence erupted between two communities at Baduria on July 3 night over a Facebook post by a youth.He was soon arrested but violence broke out with mobs attacking shops and houses, torching vehicles, including those of police, and putting up road blockades.Several police personnel sustained injuries as the violence spread to various pockets in Basirhat.