The Virtual Shtetl paragraph above seems to be conflating various sources and time periods.
The eyewitness reports regarding Malkinia in the Ringelblum Archive
Accounts from the Borderlands, 1939-1941 relate to when Malkinia was a German-controlled border station between the German and Soviet territories.
A little east of Malkinia was a "no man's land" of about 3 km that established separation between the Germans and Soviets.
In this strip, Jews camped out, unable to cross either border. The Germans encouraged the Jews to leave and didn't want them back, and the Soviets didn't keep the border open at all times to allow the free flow of Jewish refugees to the east. Seems like most were attempting to flee to Bialystok.
Eyewitnesses report hundreds to thousands of people at a time in these open fields. The vast majority were Jews, and small numbers of Poles who came to do business (selling coffee to refugees, smuggling, extortion, etc.).
The accounts don't mention any "transit camp" at all. There seems to be nothing official run by the Germans.
There are reports that Jews were taken aside at the Malkinia station and searched and robbed by German border guards. Then they were just set free to walk east.
They either walked northeast following the railroad tracks.
Or they walked directly east towards Zawisty. This follows a route "along Nurska street" and leads east out of Malkinia.
All were attempting to make it to the first two stops on the Soviet side: Zareby Koscielne, then Czyzew. From there, they traveled on to Bialystok.
Jews were just out in the open fields, staying for days before they could move on. Some were permitted across the border legally, others crossed illegally through the forests. Some got caught and sent back.
A recent
journal article on Malkinia was also published in January. It serves as a decent summary of information about the "no man's land."
The accounts I read are in the second volume of the Ringeblum Archive
books. They used to be freely accessible online, but not right now as they're "migrating to a new digital repository."
Bottom line: there seems to be no "transit camp" in 1939-1941, just a border region where Jews were attempting to cross into the Soviet Union. Then after the German invasion, this open field or forest route became obsolete since it was now all German territory. If there was a real "transit camp" in Malkinia in 1942, it was likely something different.