Security was increased at Sweden's three nuclear power plans Thursday after explosives were discovered on a truck at the southwestern Ringhals atomic power station, according to an article from The Associated Press. 

Bomb sniffer dogs detected the explosives during a routine check on Wednesday afternoon by security staff while the truck was in the power plant's industrial area near the high security enclosure, the article said. Police are investigating possible sabotage but have no suspects. The truck driver had been unaware of the explosives inside the vehicle and was not suspected of being involved, according to AP.

Bomb technicians have stated that the material lacked a detonating device, so there was no danger of an imminent explosion.The area around the truck was evacuated and cordoned off. 

Ringhals officials said that an explosion on the truck would not have caused "any serious damage" to the site but did not elaborate on how they came to that assessment. 

The discovery lead to an increase on the four-stage security risk scale for Sweden's three nuclear plants, raising the alert by a notch to 2 on a four-point scale (four being the highest alert).  

The plants, holding 10 reactors total, provides about half of the country's electricity, the article says.