Police say the person didn't mean any harm, but the poisonous flower needed to be safely and properly removed.
The hazardous material unit and Red Deer emergency services were called in.
Traffic in the area was also closed for about two hours while crews worked to secure the building, but by Monday afternoon everything was back to normal.
According to the Bison Producers of Alberta, water hemlock is the most poisonous plant in North America and is toxic to both livestock and humans.
One root of the plant can kill a cow. It grows in wet areas such as springs or stream edges.
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