A possible threat by a school district employee in Nanaimo, B.C., has prompted officials to lock the doors and post security guards at three schools and the district office.

Donna Reimer, who speaks for the school district, says its threat assessment protocol kicked in after information was received from a number of sources.

"Sometimes when something happens at a school or a workplace that's tragic, there were signs and lots of people knew bits and pieces of the story," she said.

"So if you're aware of something, you need to put something in place to have a little extra security."

Reimer says parents were told the decision to increase security at Dover Bay Secondary School and Nanaimo Secondary School, as well as Cilaire Elementary School, was done out of an abundance of caution.

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Officials say security measures were stepped up out of an abundance of caution. (Dover Bay Secondary School)

She predicts parents and students will see stepped up security measures more frequently in the future.

"They are going to see this a bit more often and that doesn't mean things are happening more often, it’s just that with our threat assessment protocol we now know it is appropriate to take steps at certain times."

Police say they are monitoring the situation and the district will assess the security measures on a daily basis.