Home insurance policies will cover much of the $2.5m (£1.7m) payout to families of victims of the Columbine High School shootings in the US in 1999.
All but six of the 36 families involved have reached a settlement in their lawsuit against the gunmen's parents and the suppliers of a gun used in the massacre.
US news reports have said the settlement mainly comprised $1.6m (£1.1m) from the parents of the student killers Eric Harris and Dylan Klebold.
The money will come from the two families' homeowners insurance.
The litigants said the parents were negligent in allowing their sons to amass a large arsenal of weapons.
Another $900,000 (£600,000) will come from Mark Manes and Phil Duran, who illegally sold the killers a gun.
Of this, $160,000 (£110,000) will be put in escrow to pay any future claims.
There is a further tentative $250,000 (£170,000) settlement with Robyn Anderson, a teenage girl who dated Klebold and legally bought him three guns.
The pair killed 12 students and a teacher and wounded more than 20 others in the 1999 attack, in which they used explosives and four guns before committing suicide.
The settlement was announced on the second anniversary of the massacre, which is still the US's deadliest school-shooting incident.