Washington, Sept. 22 (Xinhua/UNB) -- A drug-related overdose killed three people and hospitalized four others in Pittsburgh, U.S. state of Pennsylvania, police said on Sunday, citing an initial investigation.

The victims appear to have been at the same venue together, and then to have gone to a second location at a private residence where they apparently overdosed on drugs, police said.

The victims all took narcotics at the same time and the same location.

Police also said that it was not a case of "a tainted drug being passed around or distributed in large volume at a large venue which could have affected even more people."

The incident occurred in Pittsburgh's South Side neighborhood.

Five of the seven victims were found in an apartment, one in the elevator of the apartment building, and another one on a nearby street, police said.

The conditions of those hospitalized range from serious to critical.

Pittsburgh, with a population of over 300,000, is in western Pennsylvania.