Police in the US city of Pittsburgh are investigating how seven people all wearing orange wristbands were involved in an apparent drug overdose.

Three have died and the other four are in conditions ranging from serious to critical. Five were found in a flat, one in a lift and one on the street.

Police initially described it as a fatal “medical situation”.

Pittsburgh director of public safety Wendell Hissrich said all the victims were believed to be middle-aged men.

Officers also found “multiple venues” that gave out orange wristbands for events in the city. It is not yet known which of those events, if any, is linked to this incident.