Residents across Hennepin County got an early wake-up call Tuesday when civil defense sirens sounded just after 6 a.m.

Sirens sounded all across the state's most populous county despite there being no emergency or weather issues, said Jon Collins, a county spokesman.

"It was a hardware malfunction," he said.

The sheriff's office, in a statement, said the sirens are tested internally daily — a test that does not sound the sirens. Tuesday there was a "momentary computer hardware malfunction during the daily test," the statement said. The system has since been repaired and is functioning normally.

Five hours after the rude wake up, residents got a tweeted apology from the county's emergency management Twitter account (@HennepinEM). "Apologies for inconvenience/confusion from this morning siren," the tweet said, adding that a Thursday test was on schedule.

Some like Lily Dzubay said it sounded like an air raid siren. "Talk about freaking someone out. My heart is still racing," she said in a Facebook post.

Others took it in stride and made light of inconvenience through light-hearted posts on social media.

Authorities across the county issued Twitter messages assuring people that there was no emergency or weather problem, even though this is Severe Weather Awareness Week. Tornado sirens will be tested as part of a drill but not until Thursday at 1:45 p.m. and 6:55 p.m. (Let's hope it's not a.m. this time.)

Still, many were rousted out of bed early and annoyed due to the loud sirens.

"Minneapolis, what's up with the 6:10 a.m. tornado/weather siren? It's clear and beautiful and EARLY," said Lauren Fichtel on Facebook. "Thanks for stealing my final hour of sleep."

Tim Harlow • 612-673-7768