Breaking News

A woman was stabbed at Art Basel -- the world famous Miami art show attended by the likes of Kylie Jenner, Lenny Kravitz and Leonardo DiCaprio -- and onlookers thought it was part of the act.

According to the Miami Beach PD ... a fight broke out near an exhibit by artist Naomi Fisher and a woman was stabbed in the neck and arms. Reports say one witness thought the blood was part of a performance art act.

Even after cops responded ... some thought the police tape was part of the show.