The Swanage lifeboat took part in a search off the Dorset coast after reports of a red flare.
RNLI volunteers from Swanage were called to assist Poole RNLI to locate the source of the flare, an international distress signal, in the early hours of Wednesday morning in Poole Bay.
While the search was ongoing, just after 1.15am, the Swanage all-weather lifeboat crew spotted another red flare towards Boscombe Pier.
An RNLI spokesman said: "Halfway between Bournemouth and Boscombe pier a white parachute flare was fired to illuminate the area.
"Again, nothing was found.
"Investigations then started ashore as it was becoming increasingly likely that the red flares had been fired from the shore.
"We'd like to remind people that firing a red flare in anything other than a distress situation is an offence."
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