Three German tourists face possible financial penalties after being accused of defacing property at Joshua Tree National Park in California.

Park authorities accused the trio of firing paintballs at signs, bathrooms and dumpsters throughout the park.

They said the damage was discovered on Sunday after a park ranger found “fresh yellow paintball splatter on structures and signs” during a campground patrol.

Park rangers then questioned the tourists, who admitted that they had fired paintballs in the park with a compressed paintball gun and slingshots, authorities said.

Vandalism of a US national park carries a maximum penalty of $5,000 (£3,919), as well as the possibility of a prison sentence for up to six months, according to the National Park Service (NPS).

“Defacing or altering the NPS landscape, no matter how small, is against the law,” said Joshua Tree National Park’s acting chief ranger Jeff Filosa in a statement on Thursday.

“It diminishes the natural environment that millions of people travel the world to enjoy,” he said, adding that “the park is regularly tasked with removing graffiti of all types, using time and resources that could be better dedicated to other priorities”.

According to the NPS, park rangers confiscated three slingshots, a paintball marker, paintballs and other equipment as evidence from the tourists.

They also found that at least 11 roadway signs near the west entrance of the park had been shot with yellow paintballs.

Staff have since been tasked with cleaning up the park.

The park service did not name the tourists but has said that they were visiting from Germany.

Over three million people visit Joshua Tree National Park each year, according to the NPS, drawn by its “funky” Joshua trees, animal life and vistas.

It spans nearly 800,000 acres (1,250 sq miles), making it larger than the entire state of Rhode Island.

The Joshua tree, a yucca, lives for an average of 150 years. During a partial US government shutdown in 2019, a small number of the park’s eponymous trees were destroyed by vandals.

Conservationists warned at the time that because the trees grow so slowly it could take more than a hundred years to reverse that damage.

In 2021, a California couple was fined $18,000 for cutting down 36 Joshua trees north of the park to build a new home.

There have been other instances of vandalism at national parks across the US.

On its website, the NPS stated that it “is extremely difficult”, “costly and time consuming” to remove graffiti and other damage from park property.