The hide was found in the grounds of a former convent at Cornakinnegar Road area of Lurgan following a considerable search operation which has been ongoing since Thursday night.
To date three finds have been discovered.
These include a shotgun, long barrelled rifle, pistol, detonators, ammunition, constituent parts of home made explosives, other bomb making components including partially constructed devices.
Detective Superintendent Karen Baxter from the PSNI’s Terrorist Investigation Unit said: “All of these items will be subjected to a detailed forensic examination.
“Until this has been completed, it is too early to link these items to any particular grouping, but we are following a number of lines of enquiry.
“It is clear that the people who were hiding these components had one clear aim in mind – to kill and maim.
“I believe that all these items would have been used to make explosive devices and cause terror within the community.
“I have no doubt that we have removed a lethal threat from the streets of Northern Ireland but I would ask the public to remain vigilant, wherever they are and whatever they are doing.
“If people report suspicious activity to police, we will act on it to keep people safe.
“We apologise that the railway line has closed for the second time in 24 hours and may remain closed for some time while a full clearance operation is carried out, but I hope people will understand the need to put public safety first.”
“I would like to thank members of the public for their patience and would appeal to anyone who has any information about this incident to contact Detectives on the non-emergency number 101.
“Or, if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”