VANCOUVER - Vancouver police have issued a warning about a powerful drug that was stolen during a pharmacy robbery.

Police call fentanyl an "unforgiving drug," saying it's much more lethal than heroin.

Sgt. Randy Fincham says fentanyl skin patches were among various prescription drugs stolen by two suspects who forced their way behind the pharmacy's counter on Friday.

He says drug users should beware of the risks associated with the pain killer, which is increasingly being used on the street.

Police are asking anyone with information about the heist on the south side of the city to call them.