By By Leigh Goessl Jun 21, 2012 in World Stockholm - Authorities in Sweden have raised the threat level at its three nuclear facilities on Thursday. This decision was made after explosives were found on a truck located on the premises on Wednesday. According to The explosive had been placed underneath one of the truck's steps where the fire extinguisher is located, although no ignition device was present with the materials, reported “The truck was entering the guarded area when the device was found by the plant’s own sniffer dogs,” said police spokesman Tommy Nyman. No additional explosives were found after an extensive search. “They have all raised the threat level as a precaution,” said Maria Stråhle at the Swedish Radiation Safety Authority (Strålsäkerhetsmyndigheten) to news agency TT (courtesy of The Local). Authorities have classified this incident as a "suspected sabotage attempt". "We don't know what the idea behind this was, what was the plan and what may have failed. These are some of the questions we will try to answer with our investigation," spokesman Ingmar Nilja said, reported Market Watch. The materials found had been sent off to the National Laboratory of Forensic Science for testing. At this time, it has been confirmed the device was an explosive. An investigation has been launched and authorities plan to retrace the truck's movements to speak to anyone that would have come into contact with the vehicle or may have information. At this time officials have not identified any suspects. Police spokesman Tommy Nyman told the Yesterday, during a routine check, an explosive was found on a truck located on the premises of the Ringhals nuclear facility, causing authorities to raise the threat level to the second-lowest level.According to The Local , the device, described as being the size of a "small fist" shaped like a "plastic explosive", was found on a large truck that was returning to the reactor area.The explosive had been placed underneath one of the truck's steps where the fire extinguisher is located, although no ignition device was present with the materials, reported Market Watch “The truck was entering the guarded area when the device was found by the plant’s own sniffer dogs,” said police spokesman Tommy Nyman.No additional explosives were found after an extensive search.“They have all raised the threat level as a precaution,” said Maria Stråhle at the Swedish Radiation Safety Authority (Strålsäkerhetsmyndigheten) to news agency TT (courtesy of The Local).Authorities have classified this incident as a "suspected sabotage attempt"."We don't know what the idea behind this was, what was the plan and what may have failed. These are some of the questions we will try to answer with our investigation," spokesman Ingmar Nilja said, reported Market Watch.The materials found had been sent off to the National Laboratory of Forensic Science for testing. At this time, it has been confirmed the device was an explosive. Ringhals produces about 20 percent of the nation's electricity.An investigation has been launched and authorities plan to retrace the truck's movements to speak to anyone that would have come into contact with the vehicle or may have information.At this time officials have not identified any suspects.Police spokesman Tommy Nyman told the Associated Press , "An outsider has obviously placed them on the truck. We're talking to the truck driver and are trying to map out her movements within the (Ringhals) premises throughout the day." More about Sweden, ringhals, Nuclear power plant, Nuclear power, Nuclear reactor More news from Sweden ringhals Nuclear power plant Nuclear power Nuclear reactor Explosives threat level