Just Stop Oil protesters have thrown orange paint over a garden at the Chelsea Flower Show in London.
The Metropolitan Police said three people were arrested on suspicion of criminal damage.
In a video of the incident, bystanders can be heard shouting for security as a woman grabs a hose and douses the protesters with water.
A witness can be heard shouting: “You morons – all you’re doing is ruining them, you prats.”
In a statement, Just Stop Oil confirmed three women had thrown paint over the RBC Brewin Dolphin Garden, designed by Paul Hervey-Brookes, an award-winning garden designer, after stepping over a rope barrier at 9am on Thursday.
The three women named by JSO were Stephanie Golder, 35, Naomi Goddard, 58, a retired landscape engineer, and Rosa Hicks, 28.
In a statement released after their arrests, Ms Goddard, from Hebden Bridge, West Yorkshire, said: “I know that by carrying out this action, I risk losing my job, my livelihood and my reputation, but it is what I have to do right now.
“We all need to do everything in our power to stop this madness continuing.
“There is a better, cleaner, safer future, but only if we fight for it.”
The Met said three people were arrested at the scene on suspicion of criminal damage and that “enquiries are ongoing.”
Ms Golder, from Southend, Essex, added: “I disrupted the Chelsea Flower Show to ask the visitors, exhibitors and the RHS to pick a side; to stand for good over evil, life over death, right over wrong; to stand with the young and the billions of people in the global south whose lives are being cut short by climate collapse.
“If you love gardens or growing food, you must join in civil resistance against new oil and gas.”
The incident comes after activists from Just Stop Oil – which is campaigning to end all new fossil fuel projects in the UK – interrupted the World Snooker Championship at the Crucible last month by throwing orange powder paint across a snooker table.
On Wednesday, six protesters were arrested on Marylebone Road, central London, the group said.
The RHS Chelsea Flower Show began on Monday and is running until Saturday.