A convicted sex offender opened fire at a birthday party in northern Kentucky, killing four people and injuring three others, local officials say. The suspect later killed himself while being chased by police. The incident happened at around 2:50 a.m. on Saturday when officers responded to reports of a shooting on Ridgecrest Drive in Florence, a city in Boone County, about 9 miles southwest of Cincinnati. “When officers arrived, they still heard shots being fired and they approached the residence,” Florence Police Chief Jeff Mallery said. “When they got to the residence, they saw multiple vict…