(CNN) — The University of Southern California has sent students another letter addressing the high number of student deaths this semester, this time warning them about the dangers of opioid abuse — and the risks that some recreational drugs may be tainted.
Nine USC students have died since the start of the semester — an unusually high number that moved officials to send two letters addressing students’ concerns in four days, including the latest on Tuesday.
Four are believed to have died of overdoses of drugs and/or alcohol, USC public safety Assistant Chief David Carlisle told CNN.
The county coroner hasn’t issued official causes in those cases because toxicology tests are pending, Carlisle said.
Tuesday’s letter did not break down the causes, or even mention that drugs were suspected in some of the deaths. But it did say: “We need you to be aware of the dangers posed by drug use.”
“In particular, we want you to be informed about the dangers of abusing opioids,” reads the letter, written by student affairs Vice President Winston Crisp and other USC officials.
“The effects of alcohol mixed with these drugs can be fatal. In addition to the direct effects of each substance, drugs shared for recreational use can be mixed with other substances to increase its effects, sometimes without a user’s knowledge. The practice is rising and is linked to overdose and death.”
This letter, like the one sent days earlier, also encourages students to seek mental health care. It notes the school has hired more mental health counselors and has opened a psychiatry practice in the student health center.
Three of the nine deaths are believed to have been by suicide, school officials have said. One of the nine students died after being hit by two cars while walking on a freeway in August, officials said.
The university says it typically sees between four and 15 student deaths per year in its community of about 47,000 undergraduate and graduate students.
Three USC students have died since Friday
Three of the students died in a four-day period starting Friday. The causes in those cases haven’t been released.
USC President Carol Folt and three other officials sent the first letter to students Saturday, partly to counter rumors that suicide was suspected in most of the cases, and partly to urge students to seek help if they need it.
“These student losses are devastating and heartbreaking for all of us,” the letter reads. “People are searching for answers and information as we attempt to make sense of these terrible losses.”
“There is a great deal of speculation about the causes of these deaths and most are being attributed to suicide. This is not correct,” the letter reads. “These tragic losses have resulted from a number of different causes.”
‘Nothing is more important than your well-being’
Saturday’s letter urges students needing help to call the school’s 24/7 wellness hotline. It also asked people who are concerned about others’ well-being to contact its Trojans Care 4 Trojans intervention program.
“Nothing is more important than your well-being and we urge anyone who needs assistance tonight or this weekend to reach out to our counselors, public safety officers or staff,” the letter reads.