Some Colorado cities tested their outdoor warning sirens Wednesday.

The annual audible test happens at the start of tornado season in the state. The city tests the sirens monthly but without the blaring sound.

In the basement of Denver's City and County building, one system has the power to turn your quiet morning stroll down the 16th Street Mall into a puzzled walk.

"What is that?" asked one woman downtown.

Outside, 86 tornado warning sirens across Denver went off simultaneously. The loud sound caused some to stop and look around. But in Denver's Emergency Operations Center, it was quiet. If you're not paying attention to a simple click of a mouse, you'll miss the sirens turning on.

"That's called anti-climactic," said Ryan Broughton, executive director of Denver's Office of Emergency Management.

The siren test happens once a year to make sure everything is working properly. Like a fire drill, it gives people the chance to practice what they should do in a real emergency.

People in Downtown Denver didn't do what city officials would prefer. Many stared at the sky, took out their phones to record the noise and plugged their ears as they continued walking down the street.

"That's the normal response. However, what we're looking for is a response where they immediately seek shelter," said Broughton.

Some locals know the drill but decided to stay outside.

"I videoed it live on Facebook," said Casey Roby with a laugh.

"What are you supposed to do?" asked Eni Sharkaj, who is visiting from Florida.

Broughton says go inside.

RELATED: What to do in a tornado warning

"Not behind a window, not standing out at the window or on your porch looking at the storm. You need to go into the deepest, innermost portion of your house," he explained.

While the Office of Emergency Management prepares for the worst, some state newbies aren't too concerned.

"Y'alls Colorado tornadoes ain't like our Alabama tornadoes," said Broderick Sutton. "Out here people kinda go inside and they ain't gotta worry about it."

While we're not here to compare whose tornadoes are bigger, the important thing is to have a plan if and when one rolls into Denver.

For the most part, the siren test could only be heard outside. That's because the system is designed to give people who are outside additional time to seek shelter. If the sirens were to warn people indoors, the city would need an additional five to six times the number of sirens. Right now, they rely on cell phone notifications to do that job.