Construction workers in northern Poland have unearthed a World War II-era mass grave containing what are believed to be the bodies of 1,800 German men, women and children who disappeared during the Soviet Army's march to Berlin. Poles digging at the site of a planned luxury hotel in Malbork - which was called Marienburg and was part of Germany during the war - excavated a bomb crater at the foot of the city's famous 13th century Teutonic Knights fortress, authorities said Monday. The workers found a small group of bodies in late October and halted digging to allow prosecutors to investigate. After resuming work weeks later, the workers turned up dozens, and then hundreds, more corpses. They believe more may be found. It was not immediately clear how the bodies ended up in the crater but initial examinations by Polish and German experts have concluded that they are likely the remains of German citizens still classified as "missing" more than 60 years after the end of the war, town official Piotr Szwedowski told The Associated Press.