Soldiers loading the missiles failed to secure them properly and they fell, the radio station said, noting the missiles have a safety mechanism to ensure they only explode when airborne.
The missiles were damaged and removed from active use.
The head of Israel's air force, Maj. Gen. Ido Nehushtan, ordered an immediate investigation of the incident, which senior military officers attributed to negligence on the part of the soldiers loading the truck, Israel Radio said.
The incident occurred this week, but officials would not provide details of the location or the day it occurred.
Israel deploys three Iron Dome defense missile batteries in the south of the country, tasked with intercepting missiles and rockets fired at southern Israel by terrorists in the Gaza Strip.