As river levels in Poland fall to record lows amid a prolonged drought, Jewish tombstones and a Soviet fighter plane with the remains of its pilots have been found in the riverbank, evidence of Poland’s tortured 20th-century history.

Those discoveries follow the findings of stone fragments from the early 20th-century Poniatowski Bridge across the Vistula River in Warsaw, which the Germans blew up in 1944 as they crushed the Warsaw Uprising. The bridge was rebuilt after the war.

“The Vistula River is hiding no end of secrets. They are everywhere,” said Jonny Daniels, the head of Jewish foundation “From the Depths,” who waded Tuesday into a shallow area of the Vistula, picking up fragments of stones with Hebrew lettering.

Officials knew that archaeological remnants remained hidden under wild and murky waters of the Vistula River and its tributaries, but it was impossible to carry out searches for them until now. The Vistula, which flows 1,047 kilometers (651 miles) from the Beskidy Mountains to the Baltic Sea, is now at its lowest level since measurements started in the late 18th century.

On Sunday, explorers found the remnant of the Soviet fighter bomber in the Bzura River, a Vistula tributary, near the village of Kamion in central Poland. The pieces have been moved to a museum in nearby Wyszogrod for examination, with more recovery work planned for Saturday.

The head of the museum, Zdzislaw Leszczynski, told The Associated Press that parts of Soviet uniforms, a parachute, a sheepskin coat collar, parts of boots, a pilot’s TT pistol and radio equipment were found, along with a lot of heavy ammunition. The inscriptions on the control panel and the radio equipment are in Cyrillic.

It’s all part of the devastating war that played out across Poland from 1939-45: a German invasion from the west, a Soviet invasion from the east, the murder of Jews across occupied Poland and fighting between the Soviets and Germans after Adolf Hitler turned on former ally Josef Stalin.

Leszczynski said, according to witnesses, the plane was hit while flying low in January 1945 and crashed through the thick ice into the river. At the time, the German army was retreating toward Berlin before the Red Army’s advance.

“Until now, the water level did not allow for the search and there was no one willing to enter this swamp,” he said.

Russian Embassy spokeswoman Valeria Perzhinskaya said she considers the discovery important and believes the crew could be identified by the numbers on the wreckage and properly buried. About 600,000 Soviet troops were killed fighting the German army on Polish territory.

The Jewish tombstones found in Warsaw are believed to come from the Brodno cemetery in the Polish capital’s Praga district. Once the resting place for 300,000 Jews, only 3,000 tombstones remain there today. The rest were removed during and after the war, used as building materials and to reinforce the Vistula’s banks.

Two weeks ago, a man walking along the river in Warsaw came across fragments of the tombstones with Hebrew lettering. On Tuesday, he took Daniels there. In the meantime, some had already been removed, although a few fragments were still lying on the riverbed.

Now Daniels hopes to take students there to do a more thorough search and return anything he can find to the cemetery.

“Jewish history is buried in the Vistula,” he said.

(AP)