Filming the scene, which involved a student in a hospital gown being chased through the streets by FBI agents, drew the attention of a person who called police, The (Wellington) Dominion-Post said Wednesday.
"The informant said she saw what looked like some sort of pistol being passed around," police Senior Sgt. Vaughan Mead said.
The students had left the area by the time police arrived, but their car was stopped after a police pursuit.
"They said they were filming something for their media studies [class]. Unfortunately they didn't tell us, which could have had serious consequences," Mead said, adding police take reports of guns seriously.
No arrests were made but the students were reprimanded, the newspaper said.