I came across an article in Rzeczpospolita:
Here is my very quick translation (sorry for mistakes):
When on the 22 June 1941 Wehrmacht crossed Soviet border, the Bolsheviks panicked. While running away from the Germans they left everything: equipment, weapons, machines, vehicles, secret documents, even their own wives and children. There was only one thing they didn't neglect. No "enemy of the people" from the prisons in the Kresy region, could be taken over by the Germans alive.
One of the most drastic - and totally forgotten - massacres of the prisoners took place in the salt mine "Salina" near Dobromil (present day Ukraine). Already on 22 June the first trucks with Polish and Ukrainian prisoners came to the mine, where NKVD conducted mass executions. Their form was particularly drastic. People were murdered without the use of firearms - says Piotr Chmielowiec, a historian from the Rzeszów branch of IPN (Institute of National Remembrance).
Under the pile of bodies
Tied with a wire, men were forced to the edge of deep shaft. Then the female NKVD functionaries hit them with hammers used to crack the stones. The victims fell down the shaft. Those who were only injured sunk in the brine or suffocated under the piles of bodies.
There is only one known case of a man surviving the executions. "They brought him to the mine, hit with a hammer and he fell down the shaft - said the friend of the survivor - The shaft was filled with dead and half-dead men. Everything was breathing, moving, but there was little brine so he didn't sunk. After some time everything got quiet and at night he came out."
In the mine, the NKVD separated the men from the women. The women were taken to the nearby chapel, built "in Polish times" for the miners. They were murdered there. Supposedly an act of profanity took place there. One of the victims was crucified by the Soviets to the wall of the chapel.
The people killed in the mine were among others "Polish enemies of the people" marched from Przemyśl. At the same time the NKVD conducted a bloody massacre in the prison in Dobromil. People were murdered in the yard, on the stairs, in the cells. The local inhabitants of the town could hear terrible screams and shots from behind the wall - says Chmielowiec.
Some of the prisoners were killed with a shot to the back of the head, others with blunt tools. Wood storage was one of the killing places. The executioner used a 5 kg hammer attached to a thick rod, to crack the victims heads. The killer was a local NKVD collaborator of Jewish origin named Grauer or Kramer.
The director of the prison couldn't stand the massacre. He approached the NKVD officer Aleksander Malcew and suggested to use firearm to kill people. "If you say so, then you are the same as them" - the NKVD officer supposedly replied. He pulled the nagan revolver and shot the prison director.
Blood to the ankles
It is estimated that in Dobromil and the mine from 500 to well over 1000 people were murdered. Just before the entering of the Germans to the town (27 June) the Soviets escaped. We have testimonies of people, who were the first to enter the abandoned prison.
"What we saw was terrifying - a witness said - the corridor was covered with blood to the ankles and with human bodies. All the cells were open and in every one of them there were bodies. Bullet marks were visible on the walls. In the pile of bodies I noticed a man, who seemed to be alive. He was shot to the back of the head. The bulled left through his eye. We took him to the local hospital."
When the Germans arrived in place, they marched local Jews to "Salina" mine and ordered them to recover the bodies from the shaft. When the exhumation was completed the SS-men murdered them - about 100 men in total. Just like the Bolsheviks, the Germans threw the bodies to the shaft and covered it with concrete. The place is left in this state to the present day.
When the Soviets reentered in 1944, you couldn't openly talk about what happened in "Salina". Sanatorium for those suffering from tuberculosis was established in the mine. The chapel, where a part of the murders took place, was converted to a canteen. Only after 1990 could the local Ukrainians build a memorial there and hold a ceremony. It takes place on every anniversary of the massacre.
This year, on Sunday, 26 June, local Poles will take part in the commemoration for the first time. The idea for joined Polish-Ukrainian commemoration of the victims came from the priest Jacek Waligóra from nearby Niżankowice. "Unfortunately Poland is not very interested in the massacre. But so many of our compatriots died there. We shall not forget them" - says the priest.
He intervened at the Rada Ochrony Pamięci Walk i Męczeństwa (Council for the Protection of Struggle and Martyrdom Sites). He just received a promise that Polish authorities will take care of commemorating Polish victims "some day". A few years passed by and nothing happened. "So we decided to take the matters into our own hands and together with Ukrainians we are going to pray for the victims of that forgotten crime" - says the priest.
The Rzeszów branch of Komisja Ścigania Zbrodni przeciwko Narodowi Polskiemu ( Commission for the Prosecution of Crimes against Polish Nation) conducted an investigation into the massacre in years 2006-2009. It was canceled because of failure to identify the perpetrators. The only murderer know by his name - Aleksander Malcew was killed during the war.