San Francisco Goodwill store employee Debra Shaw, shops inside Frank's liquor store on Haight Street in San Francisco Thursday, Feb. 22, 2018. Shaw said she was saddened and horrified by the news that three men were found dead outside a private high school in the Haight-Ashbury neighborhood. She says she walks by the school all the time and knows that drugs are a problem. (AP Photo/Janie Har)

San Francisco Goodwill store employee Debra Shaw, shops inside Frank's liquor store on Haight Street in San Francisco Thursday, Feb. 22, 2018. Shaw said she was saddened and horrified by the news that three men were found dead outside a private high school in the Haight-Ashbury neighborhood. She says she walks by the school all the time and knows that drugs are a problem. (AP Photo/Janie Har)

SAN FRANCISCO (AP) — Public health authorities are warning against the dangers of buying drugs potentially laced with fentanyl after three men were found dead near a school in San Francisco’s historic Haight-Ashbury neighborhood.

It’s unlikely the medical examiner’s office will determine the cause of death Thursday, but the department wanted to alert health care officials and drug users, said Rachael Kagan, a spokeswoman for the city’s Department of Public Health.

“People who buy drugs on the street are at risk of purchasing drugs contaminated by fentanyl, which is a very strong opioid, much more potent than heroin,” said Dr. Tomas Aragon, San Francisco Health Officer.

ADVERTISEMENT

“It is essential for their safety to carry naloxone in case of overdose. It is a matter of life and death,” he said.

The bodies were discovered Thursday morning by a security guard at an elite private high school.

San Francisco Police Officer Robert Rueca said officers received a call at 4:35 a.m. to check on three unresponsive men on the street. Officers attempted life-saving measures and called medics, but the three men could not be revived.

There is no evidence of foul play and the deaths do not appear to be weather-related, Rueca said. He said police do not know where the men lived, but it was not at the location where they were found.

San Francisco has been going through a cold snap and authorities have increased overnight shelter space for the week.

Residents and workers were saddened by the deaths but noted they occurred in a neighborhood known for its homelessness and drugs. The neighborhood is a popular destination for tourists drawn to the nostalgic scene of the 1960-70s hippie culture.

The bodies were found near The Urban School, a private $45,000-a-year high school one block away from Haight Street and its colorful shops selling tie-dye T-shirts and pot paraphernalia. The school sits across from a church on a residential street of well-kept houses and apartment buildings, and next to a preschool where kids could be heard playing.

Urban School spokeswoman Kristen Bailey said in a statement that the three men have “no connection to Urban, and the police assure us there is no danger or threat to our students, or faculty and staff.”

Debra Shaw, who works as a processor at Goodwill, said she walks by the school all the time and knows that drugs are a problem. “It’s horrible,” she said. “I have seen people come into the dressing room and shoot up and I have took the needles out and threw them away.”

San Francisco has also grappled with an entrenched homelessness problem despite its thriving tech economy.