A mother ignored coronavirus distancing rules and let her son leave home without good reason, police have said.
The 17-year-old was found at about 02:00 GMT in the Sheepmount area of Carlisle after reports of stone throwing and cars being damaged, Cumbria Police said.
He refused to say why he was there or give his details, the force confirmed.
Temporary Ch Supt Rob O'Connor said people needed to follow guidance and stay at home.
"The last thing we want to do is to fine anyone and unfortunately in this case we had to take steps to get the message across," he said.
The boy was detained on suspicion of resisting arrest, police obstruction and in connection with a previously reported burglary.
He was released while investigations continue.
The force said officers had spoken to him on a number of previous occasions about walking the streets without reasonable explanation.