Up to six explosions were heard across the Colne Valley and Holme Valley as police carried out controlled explosions following the discovery of the items at a property, believed to be in Sycamore Avenue, Golcar, in the early hours of Saturday.
A pensioner has been arrested. It is believed the items, which were blown up by bomb disposal experts, may have been homemade fireworks.
A police spokesman said: “Officers searched a property in the Golcar area in connection with an ongoing police enquiry. During searches of the property, a number of potentially explosive substances were identified.
“The Army’s Bomb Disposal Unit attended to assess material and arranged for its safe removal. A controlled explosion was later carried out to dispose of the items.
“A 70 year old local man has been arrested on suspicion of explosives offences and detained for questioning. Enquiries are ongoing.”
The explosions could be heard for miles around, with many people woken between 4am 6am.
People took to social media to try to establish what had happened.
One resident in Meltham tweeted that vibrations had been “felt through the floor. First thought earthquake, second explosion.”
Last night whilst in bed I heard bomb like noises and just found out an army bomb disposal team found army explosives in golcar— Lucy Irving. (@lucyirvingxx) April 2, 2016
Another reported six “extremely loud bangs” heard from the edge of the moors two miles outside Marsden.
“It’s raining. But sound doesn’t rumble like a far off storm. Sounds slightly like a bomb.”
Others thought it was a sonic boom from an aircraft – or that aliens had landed.
Andrew Parker tweeted the Examiner to say: “We’re in Lindley and my wife said there was about 45 minutes of thunder during the night.”
Someone else thought it was his “problematic boiler” playing up in Fixby!
Shirls tweeted: “I’m in the Holme Valley and it woke me a couple of times. I felt vibrations too. Wondered if it was an earthquake.”
Examiner reporter Joanne Douglas, of Slaithwaite, tweeted: “Anyone in Colne Valley area hear a series of loud bangs about 4.45am? Sounded like bombs going off.”
A police spokesman added: “We recognise that local residents may have concerns as a result of this activity but we would like to reassure them that public safety has remained the priority of the investigating officers at all times.
“Precautionary measures were taken at the earliest opportunity to ensure the property presents no risk to the local community.
“Searches of the property continue and we are grateful for the patience and cooperation of local residents during this time.”