Deputy Director Vinod Krishna Singh said that the youths were found in suspicious circumstances in the core zone where wire traps had been laid.
Some more wire traps were recovered from the houses of nabbed youths identified as Chunna, Manoj and Anuj, he added.
A red alert was sounded after recovery of the wire traps from the core zone in the reserve, he said.
All Dudhwa Tiger Reserve officials, field staff, watchers and guards had been instructed to keep a close vigil in the sensitive areas particularly water bodies where wild animals move frequently.
"We have planned to set up night-vision enabled cameras in the sensitive areas to keep watch over any activity," he said.