D.C. Fire and EMS Department crews and ambulances responded to Third and E streets NW on July 18, 2018, to evaluate 11 suspected overdose patients. (Clarence Williams/The Washington Post)

Three people died after using K2, or synthetic cannabinoids, during a recent spate of overdoses in the District, according to the city medical examiner’s office.

The Office of the Chief Medical Examiner looked into six deaths that officials suspected were overdose cases and determined that half were related to a synthetic version of marijuana, according to a statement Thursday night by Cheryle E. Adams, special assistant to the chief medical examiner.

Officials declined to release personal details about the deceased, including the dates they died, their gender or their age. The statement said that two of the deaths showed the presence of other drugs in addition to K2, such as cocaine and fentanyl.

The lethal overdoses were linked to a sudden spike in suspected K2 overdoses in mid-July that left the D.C. fire department treating and transporting patients from across the city.

Crews have continued to evaluate and transport multiple patients with suspected K2 overdoses daily in the weeks since, although the numbers have dipped dramatically since a six-day period in July in which medics evaluated more than 170 suspected K2 patients and took 122 to the hospital.

Amid that surge, multiple medical crews arrived to an area of just a few blocks near police headquarters on a single Wednesday night.

In response, District agencies launched a public campaign to warn residents to steer clear of the synthetic drug, especially among the homeless population that accounted for much of the uptick in overdoses.

The city’s Department of Forensic Sciences in mid-July also confirmed that FUB-144, a synthetic marijuana that the Drug Enforcement Administration has tracked in other cities, had been confiscated for the first time in the District.

During the first 10 days of the July wave, EMS crews served more than two dozen patients daily. Throughout August, the daily number of transports has been about a dozen or fewer, fire department records show — amounting to a total of 785 people since July 14 examined for suspected K2 overdoses, with 602 of them taken to hospitals.

D.C. police Lt. Andrew Struhar said that investigators continue to trace the sources and suppliers of the drug but that it still isn’t clear what chemicals or dosage may be the cause of the heightened harmful effects.

“The dangerous nature of this is apparent, whether it’s used alone or with other substances,” Struhar said

Despite an intensive public awareness campaign, authorities still see many users as either addicted or too attracted to the synthetic cannabinoids.

“Even after interviewing many of the people on the street, they didn’t know or didn’t care what it was. It was just a high, and it was inexpensive,” Struhar said.

Of the six apparent K2 overdose deaths from July, three proved to be from causes other than synthetic-marijuana use. Two deaths were from heart disease, and a third person died of a fentanyl overdose, the medical examiner ruled.

As K2 use appears to have tapered in the District, its effects seem have surfaced elsewhere, including a recent clutch of overdoses in New Haven, Conn.

Officials there reported dozens of illnesses last week believed to be connected to synthetic marijuana.

Over the course of 24 hours, more than 70 people overdosed on what authorities considered to be synthetic marijuana, with dozens of those overdoses occurring on the New Haven Green, a historic downtown park bordering the Yale University campus.