HALIFAX -- Dalhousie University has issued a warning after four students reported they were served alcohol spiked with an unknown substance.

A security bulletin by the Halifax school Friday says the spiked drinks were allegedly served at an organized off-campus party.

The bulletin says students should pour their own drinks and not leave drinks unattended.

It urges students to intervene in instances of sexual violence by challenging the perpetrators and supporting the survivors.

Dalhousie security says if a student feels they have been drugged or sexually assaulted, they should seek medical attention or call a sexual assault response line.