From securityweek.com
“The two men arrested are Polish citizens,” said Tomasz Krupa, a police spokesman in the eastern city of Bialystok where the arrest occurred.
Police also seized radio equipment from the apartment where the men, who are 24 and 29 years of age, were detained.
On Friday night, the radio communication network of the Polish PKP railway was hacked near the northwestern city of Szczecin leading to the issuing of several stop signals which brought to a standstill or delayed some 20 trains.
Traffic resumed a few hours later, according to PKP.