Two men have been arrested over the theft of 12 handguns from the Ministry of Defence (MoD), police said tonight.
The weapons were reported missing from MoD property in Wiltshire on Wednesday.
Eleven of them were subsequently recovered from a house in High Wycombe, Buckinghamshire.
Police do not know where the remaining weapon is, despite searching two other properties in the High Wycombe area yesterday.
A 22-year-old man was arrested on suspicion of theft at Draper Court, where Thames Valley Police discovered the handguns, and later released on bail.
A 28-year-old man was arrested for handling a firearm, and was still being questioned by officers this evening.
Detective Inspector Kev Mahon, who is leading the investigation, said: "We are continuing to work closely with the Ministry of Defence and every effort is being made to recover the outstanding firearm.
"I urge anyone who knows anything about this incident to come forward."
Anyone with information should contact Det Insp Mahon via the police inquiry centre on 0845 8 505 505 or call Crimestoppers on 0800 555 111.