A 25-year-old man was badly injured in a blast which occurred in Karmiel on Wednesday.
Police believe the blast resulted from an explosive device, and believe the youth was attempting to assemble the device, when it went off.
The incident is criminally-related, police said.
Paramedics and a police bomb squad unit were called to the Karmiel cemetery following reports of a blast shortly before 9 am.
The injured man was taken to the Nahariya hospital. Police have obtained a court-ordered media ban on details of the investigation.
Also in the North on Wednesday, police discovered an arms cache in a Kiryat Bialik apartment, seizing grenades, a pistol, explosive devices, and various ammunition.