It happened at home at Wilson Avenue and Bunce Road around 3 p.m. Monday.
Ron Seaford watched as fire crews rescued the two unconscious women from a mobile home. The incident was treated as a hazardous materials exposure.
"They were not moving very good," said Seaford. "That's why they laid them on the ground and ripped their clothes off."
Fayetteville Police Capt. Anthony Kelly told reporters that officers and firefighters responded to a call of a suspicious package and brought the unidentified women out of the house and took them to Cape Fear Valley Medical Center, where their conditions were unknown.
Investigators said the women apparently ingested the drug. One police spokesman initially said the package contained heroin laced with acetyl fentanyl, but later said laboratory testing would have to be done to positively identify the substance.
On the street, the acetyl fentanyl combo is called "china white." Police say it is as lethal as it is potent. Last week, state DHHS officials released a statement warning the drug is up to five times more potent than heroin, and suspected in three recent deaths in North Carolina.
Nationwide reports say heroin laced with fentanyl is stronger, cheaper and more desirable on the street. However, a user who overdoses can quickly lose consciousness, and stop breathing.
Police said one of the victim's fiancé found them unconscious and on the floor, and called 911. That may have saved their lives.
Two young children were in the home at the time of the incident.