Darth Vader costume causes evacuation at high school

A student who dressed as Darth Vader on Star Wars day has caused an evacuation at a US high school.

The student, who was celebrating popular sci-fi day, spooked a parent who then called police.

The parent at the Ashwaubenon High School in Wisconsin told police they saw a suspicious figure wearing all dark clothes and mask while carrying a large bag.

A police spokesman told a local Fox affiliate "that outfit actually looked like he might be wearing a bulletproof vest or a flak jacket".

School officials asked students and teachers to gather at designated rally points and put the school on lockdown.

The date May 4 is styled as "May the Fourth Be With You" after the famous line in the movie series, "may the force be with you".

The school posted on Facebook that the "student will be held accountable" as costumes are not allowed at the school.

Police said it was a "good learning lesson" for the student involved and that they would not pursue any punishment.