On a post to its Facebook page, Mountainview High School said the community had "tragically lost another young person this week".
"We are in uncharted territory at this time with the recent tragic events coinciding with a lockdown," the post says.
"But we believe that preventative measures are our best defence to keep our tamariki safe."
The young person had "no direct relationship" with the school.
The school was unable to share details on the death but felt it needed to make parents and caregivers aware "to help minimise any further impact on our tamariki".
"In a time when social media is the source for most information young people are exposed to, we are concerned that this information is already widely circulating.
"This information may not be accurate or helpful.''
The post also included a number of resources and helplines to help families "'check in' on their child's wellbeing".
"But we believe that preventative measures are our best defense to keep our tamariki safe."
"Many young people do amazing support roles with their friends and this can take its toll on them," the post said.
Earlier this month, Javarney Wayne Drummond, 15, Niko William Hill, 15, Jack "Jacko" Wallace, 16, Joseff "Joey" McCarthy, 16, and Andrew Goodger, 15, were all killed when the Nissan Bluebird they were travelling in smashed into a concrete power pole.
Only the driver, 19-year-old Tyreese Fleming, who was on a restricted licence, survived the smash.
He was taken to Timaru Hospital with moderate injuries but was recently discharged.
In the aftermath of the fatal crash, school in the area had counsellors available and are being supported by the Ministry of Education.
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633 or text 234 (available 24/7)
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (12pm to 11pm)
• Depression helpline: 0800 111 757 or text 4202 (available 24/7)
• Anxiety helpline: 0800 269 4389 (0800 ANXIETY) (available 24/7)
• Rainbow Youth: (09) 376 4155
If it is an emergency and you feel like you or someone else is at risk, call 111.
