A cyclist was thrown from his bike when he was caught in a metal wire trap strung across a road.
The fishing wire caught the 31-year-old man on the neck as he approached the roundabout on Tuckton Road, in Bournemouth, Dorset.
Police are hunting for the "reckless" people who risked lives with the trap.
The cyclist was on his way home to the East Howe area of Bournemouth from Hengistbury Head when the incident happened at 1700 BST on Sunday.
He fell into the road and suffered minor lacerations on his neck.
Sgt Mark Palmer, of Boscombe police, said they were "treating this incident extremely seriously".
He said: "Whoever strung this wire across the road was acting in a mindless, reckless and extremely foolhardy way.
"The wire could have seriously injured or even killed the cyclist - he could have been decapitated.
"If the wire had not injured the man, he could have been run over by other vehicles after being thrown off his cycle into the road after hitting the wire."
The fishing wire was so thin it was almost impossible to see, police said.