Police say the 16-year-old New Westminster girl who died of an overdose Friday thought she and her friend were taking MDMA.

The second girl remains in hospital in stable condition after the two bought and ingested pills from a street level dealer.

"There's communication between the girls and the dealer which we have looked at," said Sgt. Andrew Perry of the New Westminster Police.

"It is clear that these students thought they were getting MDMA, that's what they agreed to purchase and that's what they thought they were taking. Whether or not that was indeed what they got, we don't know."

Fentanyl factor?

Perry says toxicology reports aren't expected until the end of the week, and, until then, it's impossible to say what the substance was and whether it contained fentanyl.

File photo of MDMA, also known by its street names 'ecstasy' and 'molly.' The two girls who overdosed had arranged to buy MDMA from a dealer, according to the New Westminster Police. (CBC)

"In this day and age, absolutely, we are concerned that [fentanyl] may be a factor," he said.

Perry says its not clear whether the person the girls were communicating with was the same person they bought the drugs from.

According to police, the girls took the drugs before going to hang out at Moody Park. One girl collapsed in the 1300 block of Hamilton Street soon after leaving the park.

Friend called 911

Perry said a friend who was with the girls called 911.

"Unfortunately, it didn't help the person who died but it did help save the other girl's life," he said.

On Monday morning, the New Westminster School District sent its critical incident team of psychologists and counsellors to Power Alternate Secondary School which the deceased girl had attended.

"Power Alternate school is a very small school with only 66 students," said New Westminster School superintendent Pat Duncan. "This is a very difficult time for the families and students who knew the young ladies and our hearts go out to them."

"New Westminster is very small relative to the rest of the communities in Metro Vancouver and this has impacted the entire community."

On Friday, the New Westminster Police Department issued an urgent warning for what it calls a "lethal" strain of drugs in the city.

Perry says people using drugs, or in the presence of drug users, should never hesitate to call 911 if something goes wrong.

"Police aren't going to arrest you," he said.

Pls RT. Urgent drug related warning. Lethal strain of drug circulating in <a href="https://twitter.com/hashtag/NewWest?src=hash">#NewWest</a>. <a href="https://t.co/9PTvALr58n">https://t.co/9PTvALr58n</a> <a href="https://t.co/6x8rJJ4kCY">pic.twitter.com/6x8rJJ4kCY</a> —@NewWestPD

With files from Farrah Merali