ST. LOUIS COUNTY, Mo. – St. Louis County residents’ ears perked up a bit Friday morning after a tornado siren accidentally went off.

Around 7:30 a.m. Friday, St. Louis County residents heard a familiar but surprising sound. For six to eight seconds, tornado sirens sounded off.

The emergency system, usually scheduled to go off on the first Monday of the month, accidentally went off after the St. Louis County Office of Emergency Management tested the system.

“I don’t anticipate the event that happened today to happen again,” said Mike Clause, a spokesperson for St. Louis County Emergency Management.

However, back in November, the same incident happened.

“We added an automated process that will do that silent testing for us, without human interaction basically,” Clause said.

The director of emergency management, Michelle Ryan, reassures residents.

“In an actual siren, when we sound it, and it’s not the test, there will not be an all-clear,” Ryan said. “It’s a three-minute tone, and then it stops.”

Residents were taken aback and unsure of what to do.

“I peaked outside and did not see any storm or anything, so I kind of just assumed it was a mistake,” said J. Rutlin, a Maryland Heights resident.

“I was just concerned about what it was, I mean, it was very clearly not a tornado,” said Paul Graham, an Overland resident. “I wasn’t sure if it was some other type of siren.”