PURNIA, July 22 -- Five persons were injured, three of them critically, in an acid attack which allegedly started following a protest against caste slur in Bihar's Purnia. The injured include three youths, a woman and an elderly. Police swung into action and arrested the accused and further investigation is underway. The incident took place at Barhara market under Barhara Kothi police station Sunday evening when Rajiv Kumar, a goldsmith, and his henchmen attacked Mrityunjay Kumar (17), Himanshu Kumar (19) and Nilesh Kumar (17) as the three protested against a caste slur on them made allegedly by Rajiv. "The goldsmith and his men suddenly threw acid on the three youngsters and two persons -- a woman and an elderly man -- who were passing by, were also injured," eyewitnesses said, adding, "We rushed them to government medical college and hospital (GMCH) Purnia, they said....