CHATHAM, Va. (AP) _ Police are investigating an unknown drug that has sickened four teenagers in Pittsylvania County. The Pittsylvania County Sheriff’s Office tells media outlets that it’s working with chemists to identify the powdered substance. The sheriff’s office says the teens, aged 15 to 19, sought emergency treatment in the past week after ingesting capsules containing the substance. Police are seeking the source of the substance and advising anyone who has the capsules to not ingest them. No arrests have been made.