FERNANDINA BEACH, Fla. -- A SWAT team responded to the scene at a Fernandina Beach post office Thursday evening after receiving 911 calls about a gunman holding hostages inside the building.

A frightened witness thought it was total mayhem, a hostage standoff unfolding right before his eyes.

However, what he thought was a serious matter turned out to be big mix-up.

When authorities arrived on the scene, they found out the whole thing was part of a movie shoot.

It turned out that the movie's producers cleared the shoot with the city, but no one else was notified -- not the police department, nor the public.

The dramatic call from outside the post office came into an emergency operator just after 6 p.m. It was a potential nightmare for police -- a suspect inside a building, possibly holding hostages at gunpoint:

CALLER: "A guy got out of his car and walked into Center Street Post Ofice with a gun. It was, like, an AK-47."
OPERATOR: "OK, what did he look like?"
CALLER: "I, I, man, I really can't tell you that. I don't know."
OPERATOR: "Can somebody call the city? Right now, and tell them there's a man walking in with an AK-47 in the post office."
CALLER: "All I seen was a man walk in there with a gun. I seen him reach in the back seat of his car."
OPERATOR: "OK, what did he look like, do you know?"
CALLER: "I don't know what he looked like. All I noticed was the gun that he was carrying."
OPERATOR: "Is he in the post office now?"
CALLER: "Yeah, he's inside right now. But, I don't know why he took the gun in there, but I know it was a gun."
OPERATOR: "Do you see any of my police officers?"
CALLER: "It looks like a police officer, yeah, yeah, a police officer's in there with a shotgun."
OPERATOR: "A police officer's inside with a shotgun?"
CALLER: "No, no, no, no, no. He's coming out."
OPERATOR: "Who's coming out, sir?"
CALLER: "I don't know."

The call sent officers scrambling to the scene, but it turned out to be a false alarm. The gun was fake, part of a movie being shot by Fernandina Beach High School students.

However, police didn't know that and shut down much of the downtown area.

"The SWAT team came through and made everbody who was out here go in the back. We all had to go in the backroom, because it's all plate glass windows and obviously that's not a very good situation," said witness Rebecca Campbell, who works across the street from the post office. "People were pretty scared."

The man talking to the emergency operator was pretty scared, too; frightened and flustered by what he thought was a crime in progress.

It took about an hour before police figured out that the standoff was just a high school movie shoot, and the situation was completely resolved.

No one was hurt during the standoff, and no charges have been filed.