An alert has been issued in the London region as the number of opioid overdoses in recent days hit an 'alarming' level.

The Middlesex-London Health Unit says there have been 16 suspected overdoses since Monday in the area.

Dr. Chris Mackie, Medical Officer of Health and CEO with the MLHU said in a statement, “This is truly alarming. We haven’t seen numbers like this, especially over such a short period of time...People need to take the necessary precautions if they intend to use these drugs."

There is concern about the possibility of a new and toxic form of fentanyl arriving in the region.

London police Chief John Pare said in a media release, "The fact is tha tis impossible to know what is in street drugs, which make it critical for those who use drugs to have a safety plan."

In Woodstock alone, police responded to six incidents on Friday and Saturday.

One of those, a 17-year-old male who was taken to hospital on Saturday morning, died two days later of a suspected overdose. Police are investigating the death.

There were three other suspected fentanyl overdose deaths in nearby Brantford.

Woodstock police Insp. Marci Shelton said in a release, “We want people to immediately call 911 if they suspect someone is overdosing. Those first few minutes are critical. Those that are users of Fentanyl, no matter the colour are at risk – it is a very dangerous drug."

Officers in Woodstock say at the overdoses they have attended, the fentanyl has been green or blue in colour, and extremely toxic.

Naloxone kits, which helps temporarily reverse an overdose, are available at the health unit, the Regional HIV/AIDS Connection and area pharmacies.