Cyclists and runners are being urged to take care after a number of lethal traps were found on woodland cycle paths in Ceredigion.
The homemade devices consist of a wooden board with several six-inch (15cm) nails sticking up and could cause "serious harm".
Lampeter councillor Hag Harris said the discovery was "very disturbing".
Natural Resources Wales (NRW) is investigating and police urged path users to be vigilant.
The first spiked trap was found by Elen Page while she was out running on the path in Upper Forest, Lampeter, which is popular with runners, dog walkers and cyclists.
She found a trap embedded into a small path and concealed by twigs and leaves so she reported it to Lampeter Police Station.
She said: "I just happened to look down as I was about to step on it and I stopped myself just in time."
Mrs Page said she believed the trap was aimed at cyclists but could have caused "serious harm" to either a rider or a runner.
"It's been planted by somebody who doesn't want bikes on these paths, in my opinion." she added.
Grenville Evans and his two sons found a further four traps hidden under moss at different locations on the same path and have also reported it to police.
Mr Harris said he had met with NRW at the site.
He said: "Obviously we are very disturbed by these events. The traps could cause serious injury to anyone treading or falling on them.
"As a runner myself I have never heard of any such event in this area during the the last 40 years.
"I would ask anyone who sees anything to report it to the police and Natural Resources Wales."
Steve Cresswell, operational resource manager at NRW, said it had been made aware of the problem, staff had been out to investigate and the police had been alerted.
Dyfed-Powys Police added: "Police and Community Support Officers (PCSOs) have carried out house-to-house enquiries to make local residents aware of the items and asking them to be vigilant if using the paths in that area.
"If anyone finds more items of a similar nature I would urge them to hand them in at the police station to ensure the safety of the public."