Emergency services in the municipality of Ljusdal raised the alarm earlier this year after loudspeakers from the local ‘Hesa Fredrik’ alarm system started to go missing.

The mystery only began to be solved when a passer-by witnessed one of the speakers being stolen over the weekend and saw a so-called A-tractor, a car with a tractor engine which can be driven by teenagers, parked in the vicinity.

Police then tracked down the owner of the vehicle, and caught them with the speaker wired up to their vehicle’s sound system. 

“There it was, plugged into an amplifier in the back seat,” Peter Nystedt, head of the local emergency services, told local Ljusdals-Posten newspaper. “So you could say they were caught with their hands in the cookie jar.” 

Anyone who has been in Sweden for more than a few months will have heard the honking Hesa Fredrik alarm system, which is tested across the country four Monday afternoons a year. But to know about A-tractors, you need to have spent time driving in the Swedish countryside. 

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Hesa Fredrik sounds rather like the horn of a ship as it leaves port, which makes for a rather curious aural experience hundreds of miles inland. It was nicknamed Hesa Fredrik (“Hoarse Fredrik”) after a Swedish columnist at Dagens Nyheter in the 1930s, Oscar Fredrik Rydqvist, noted that it sounded like himself when he had a cold.

A-tractors, meanwhile, small, cut-off cars with a max speed of 30km/h and an orange warning triangle on the back, are popular with teenagers, as anyone over the age of 15 can drive one as long as they have a moped or tractor driving licence.

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Although the story might generate amusing headlines, Nystedt said that damaging Sweden’s alarm system was potentially very serious. 

The system, he told the newspaper, is “the one possibility we have for warning the public quickly”. 

“If there was an accident with dangerous chemicals or a fire, where we need to warn people, this is the system we use to do that. If the loudspeakers are stolen there are blank spots on our map, and that can have seriously tragic consequences. Every second can be important,” he said.

Many A-tractors are hand-built or hand-altered from standard cars, meaning that they are often personalised to the owner, with colours, decorations or decals reflecting the owner’s personality. They are also notorious for having loud stereo systems, sometimes leading to complaints from locals tired of listening to teenagers allegedly driving dangerously and playing loud music.

Nystedt said he suspected that the other thefts may have been perpetrated by other A-tractor-driving teenagers.