The Hollywood cavalcade descended on Cannes Saturday for the premiere of Leonardo DiCaprio and Martin Scorsese's Native American crime epic, "Killers of the Flower Moon" which received gushing first reviews.

The three-and-a-half-hour movie sees DiCaprio play alongside Scorsese's other long-time muse Robert De Niro, and charts a wave of murders among oil-rich Osage Indians in the 1920s and the birth of the FBI.

After hours of waiting in the rain that has drenched the French Riviera town all week, fans went wild as DiCaprio, De Niro, and Scorsese arrived for the premiere alongside several native Americans in traditional outfits.

Jesse Plemons, who is also in the film, arrived with his wife Kirsten Dunst, while Salma Hayek, Cate Blanchett, and Tobey Maguire were also present.

The film sees DiCaprio play a weak-willed man who marries a wealthy Osage Indian and is drawn into the machinations of his kingpin uncle (De Niro).

The first reviews were strong, with Deadline magazine saying Scorsese's first Western "packs a wallop" with "a harrowing and highly complex tale".

The Hollywood Reporter singled out DiCaprio's "excellent" performance, adding: "Scorsese has made an impassioned film that honors both the victims and the survivors."

- Frontrunners -

Elsewhere at Cannes, the competition for the festival's top prize Palme d'Or is heating up.

Another round of Hollywood royalty followed Scorsese's film on the red carpet for Natalie Portman and Julianne Moore's new film "May December," which looks at the relationship between an older woman and a schoolboy, still married years after their relationship became a tabloid scandal.

An early front-runner is British director Jonathan Glazer's "The Zone of Interest", a unique and horrifying look at the private life of a Nazi officer working at the Auschwitz concentration camp.

Critics were near-unanimous in their praise, Variety calling it "chilling and profound, meditative and immersive, a movie that holds human darkness up to the light and examines it as if under a microscope".

But there was also huge warmth for "Four Daughters", a heartbreaking documentary about radicalisation within a Tunisian family that is both inventive and engaging.

That may go down well with jury president Ruben Ostlund, last year's winner for "Triangle of Sadness", who likes his arthouse films with some lighter touches.

A total of 21 films are in the main competition, which concludes on May 27, including previous winners such as Japan's Hirokazu Kore-eda, Germany's Wim Wenders and Britain's Ken Loach.

- Ageing icons -

The weather has been untypically wet this year, but Cannes has had no shortage of splashy moments since kicking off on Tuesday with the controversial appearance of Johnny Depp, playing French king Louis XV in "Jeanne du Barry".

The festival also saw an emotional appearance from Harrison Ford, receiving an honorary Palme d'Or at the world premiere of "Indiana Jones and the Dial of Destiny".

At the risk of turning this year's Cannes into a festival of ageing Hollywood males, there was also an honorary Palme for Michael Douglas, and an appearance from Sean Penn as a grizzled New York paramedic in "Black Flies".

"Killers of the Flower Moon", which was funded by Apple, is showing out of competition.

It is the first time that Scorsese, who won the Palme in 1976 for "Taxi Driver", has presented a film in Cannes since 1985's lesser-known "After Hours", though served as jury president in 1998.