Four people were found dead inside a Fullerton apartment after a friend reported they had overdosed and were not breathing, police said.

When authorities arrived at the residence in the 100 block of Wilshire Avenue about 11 a.m. Tuesday, they discovered the bodies of four adults. The Fullerton Police Department did not provide additional information as to the age or gender of the deceased.

“There is no immediate threat to the public,” the department said in a statement.

Two women consoling each other.

Two women console each other after learning of the deaths of four softball teammates.

(KTLA-TV)

Detectives have launched a death investigation. Authorities have not confirmed the identities of the deceased, but a friend of the group told KTLA-TV that they were all part of the same softball team.

It’s not clear what, if any, drugs the individuals were using. Fullerton police could not immediately be reached for additional comment Wednesday.

But drug use has become a growing concern across Southern California in recent years, particularly with the growing presence of fentanyl in certain narcotics.

The rate of death due to opioid overdose nearly tripled in Orange County from 2017 to 2021, from 7.9 deaths per 100,000 to 23.2. The largest increase occurred during the first year of the COVID-19 pandemic, with the overdose rate rising 88% from 2019 to 2020, according to the Orange County Health Care Agency.

From 2018 to 2020, the highest rates of drug- and alcohol-related deaths in the county were predominately along the coast, but also were recorded in sections of Fullerton, Garden Grove, Midway City and Anaheim, according to the most recent data available.

In Los Angeles County, six recent fatal overdoses have been linked to kratom, a compound that is being synthetically reproduced and sold over the counter as a cure-all for a host of ailments, the L.A. County Department of Public Health announced this month.

The compound, also known as 7-Hydroxymitragynine or 7-OH, was found to be a contributing cause of death in three residents who ranged in age from 18 to 40, according to the county health department.