Coimbatore, Feb 24 (PTI) One person was injured when a motorcycle-borne gang hurled a petrol bomb at a crowd gathered outside a cinema hall screening actor Ajith Kumar-starrer "Valimai" here early on Thursday.The incident occurred at around 4.30 AM, when Naveen Kumar was erecting a flex board of the star in front of the theatre complex in Gandhipuram area here when the duo came on a bike and threw the petrol bomb at him before fleeing, police said.Kumar sustained minor injuries in the explosion, which caused tense moments in the area, they said.Police suspect rivalry between fans of the actor over erecting banners as motive behind the crime.Security has been beefed up in front of other theaters in the city following the incident. Investigation is underway, they added.Valimai, directed by H Vinoth and featuring Bollywood actors Huma Qureshi and Janhvi Kapoor among others released worldwide today. PTI NVM ROH ROH