BUCHAREST, Romania (AP) — Authorities say they are investigating the theft of 64 missile warheads from a train transporting military equipment to Bulgaria.

Interior ministry spokesman Marius Militaru said Sunday the components are not dangerous on their own — only when integrated into missile systems. Prosecutors said Monday they are investigating the theft.

Officials Monday did not respond to inquiries regarding if the warheads contained explosives.

Railway workers on Saturday noticed the seals on a carriage door were broken, and it was not properly closed when the train reached Giurgiu, a Danube port that borders Bulgaria.

Tohan Zarnesti, the Romanian company that was shipping the warheads, produces artillery ammunition, ground to ground missiles and air to ground missiles and warheads for 122mm missiles.