Swedish officials raised the alert level for the country's nuclear plants after finding explosives in a truck near the biggest plant in the country, the Associated Press reports.

Authorities say bomb sniffer dogs found the explosives near the plant near Ringhals, Sweden's second-largest city, while conducting a security check Wednesday, but did not mention what kind of material they were made of, nor how many were found. There was no ignition device attached to the explosives, so there was no danger of them going off.

The plant has four reactors and is controlled by two energy companies, Vattenfall and E.ON.

Police spokesman Tommy Nyman said authorities were still searching for suspects, but that the driver of the truck wasn't aware that he was carrying explosives.

“An outsider has obviously placed them on the truck,” Nyman said. “We’re talking to the truck driver and are trying to map out her movements within the premises throughout the day.”

News video broadcast on Barzoome on June 21 is below:

image via Agence France-Presse