Three people have died and four more were hospitalized following a “medical situation” early Sunday, Sept. 22, in Pittsburgh’s trendy South Side Flats area, Pennsylvania, authorities said.

The Pittsburgh Public Safety Department said the incident happened about 2 a.m. Sunday. Five victims were found inside the Southside Works City Apartments on Tunnel Boulevard, one was found in an elevator outside the apartment and another was found at 26th and Carson streets. Those hospitalized were in serious to critical condition.

Police earlier confirmed “multiple hospitalizations and deaths” after responding to a “medical situation.”

The initial investigation suggests drug-related overdoses, according to a press release. This was not a case of a tainted drug being passed around or distributed in large volume at a venue that could have affected more people. It appears to have been isolated to a single location, police spokesman Chris Togneri said.

The victims, who were all male, apparently were at a venue together before going to an apartment, police said in a statement. The victims were all wearing orange paper wristbands. They took the narcotics at the same time and in the same location.

Police identified two venues in the city that used orange paper wristbands for events and concerts Saturday night. Anyone who attended any of the events has no cause for concern regarding their health, according to police.

The South Side City Club Apartments said none of the victims lived there, according to a statement released to the Pittsburgh Post-Gazette.

“These were acquaintances of a good standing resident, who apparently was not in the apartment at the time the individuals were found,” the statement said. “It is our understanding that the group had attended an outside event where they may have consumed a toxic substance before returning to the apartment.”

Building spokesman Mark Winters said that it was unclear how the men were able to enter the building and apartment when the resident wasn’t there.

Pittsburgh police said they are investigating the deaths.

Anyone with information has been asked to call police at (412) 323-7141.