Hunters began detailed tests on Tuesday at a mountain side in Poland after claiming in August to have located the lost Nazi gold train.

The two hunters, German Andreas Richter and Polish Piotr Koper, are already prepared for three days of research, but are still waiting for the military to officially announce that explosives are no longer in the area of the Polish city, Walbrzych, according to Mining. However, local officials think that since winter is coming, a thorough search for the Nazi gold train will not be possible until spring.

Richter and Koper already have a scanned image of the train in the Polish mountainside, which was obtained by ground-penetrating radar.

"We already know, namely, that under the earth there is a train. We need three days of good weather to carry them out," Koper said, according to CNBC. "Now that the area is cleared of scrub these studies will be much more accurate."

Despite the discovery, spokesman for Walbrzych, Arkadiusz Grudzien, says the mining experts will not be allowed to fully penetrate the ground.

"The experts will be able to use different measuring equipment and detectors, but are not allowed to touch the ground," he said, according to the Agence France-Presse. "They won't be able to dig, or drill or introduce cameras into the ground. They're only allowed to perform a non-invasive search."

The Nazi gold train has never been proven to have existed, but it is said to carry gold, jewels, and other Nazi treasures that were hidden after World War II. One of these treasures is allegedly the Amber Room made in the 18th century and lost during the war.