The TEK was involved because the gang also had weapons. The leader of the gang was alerted from the Ukrainian side about migrants who wanted to cross and go to the west. They were waiting for the migrants at the border while they were watching the police. After, they took the migrants in cars towards the west. Apparently they asked for hundreds of dollars from the people, the ‘fee’ could even reach as high as 2000 dollars. The gang members might be sentenced to 8 years in prison if criminal conspiracy is proven.
Hvg.hu also publishes videos, one by the police and another one by TEK about the raids. (Obviously, the TEK makes much more professional videos!)