Police say no weapons were found after armed officers were called to reports of firearms in a park.
Armed police were seen running into Aberford Park in Borehamwood at the weekend, while a police helicopter also circled above.
Despite the nature of the report and serious presence that followed, police say "nothing of interest was found".
Police vehicles in Borehamwood on Saturday
A spokeswoman for Hertfordshire Constabulary said: "Police were called shortly after 5.10pm on Saturday August 1 following an incident in Aberford Road, Borehamwood.
"It was reported that three males were seen acting suspiciously and that two items, suspected to be firearms, were seen.
"Officers attended and an extensive search of the area was carried out, with assistance from the dog unit and police helicopter."
The spokesperson added: "The males were located and detained for a search but nothing was found.
"A search of the area was also carried out to check that nothing had been discarded. Nothing of interest was located and enquiries are continuing at this time."
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