The Columbus Dispatch reports that the officer knocked on the door after a man flagged down police to report that his sister might be doing heroin inside the house. When a resident slammed the door on the officer, it apparently caught the officer's hand. With his free hand, he reached for his gun and opened fire into the closed door. There were nine people in the home.
Yes, the house apparently has a reputation as being a "drug house." But there are a couple of issues here.
First, that the officer's hand was caught in the door at least suggests that he was attempting to enter the house. It is unclear from the story whether he had a warrant. A police officer can enter a home without a warrant under extreme, "exigent circumstances," such as the belief that someone is in the process of committing a violent crime. A secondhand tip that someone in a residence might be ingesting illegal drugs is not an exigent circumstance.