SACO – Police sought the source of a prescription drug that allegedly was handed out during a weekend gathering of motorcyclists, landing five of them in hospitals.

The five bikers were given medical assistance after overdosing on Klonopin or mixing it with alcohol during the Weekend Behind the Barn, an annual event that drew a crowd estimated at up to 3,200, said Sgt. Bradley Paul.

When police and rescue personnel arrived Sunday afternoon, three men were apparently unconscious, Paul said. One of the men was not breathing and had to be given CPR.

Rescue personnel from Biddeford, Old Orchard Beach, Buxton and Scarborough were summoned in response to reports that two more people were unconscious.

The victims were taken to Maine Medical Center in Portland and Southern Maine Medical Center in Biddeford, Paul said.

One man, whom Paul did not identify, remains in critical condition; the other four have recovered.

Klonopin, an anti-anxiety drug, is often subject to abuse, Paul said.

“This is the first time we’ve had anything of this magnitude there,” he said of the gathering.