While he has not been officially named by police, the suspect has been widely reported to be Kenneth Darlington, 77, a retired American lawyer and university professor who lives in Panama.
Police said on X (formerly Twitter) that a man has been arrested at the scene, where he was charged with aggravated homicide and illegal possession of a firearm.
Mr Darlington, who was born in Panama but has US citizenship, was caught up in a traffic jam on Tuesday on a highway 55 miles west of Panama City, caused by protesters campaigning against the recent deal the Panama government made to restart a copper mine.
The protest attracted a group of photographers and TV reporters to the site of the traffic block, where they had lined the middle of the highway with tyres, flags, tree branches and stones to stop the cars.
Despite the cameras, horrific video footage showed Mr Darlington, who was allegedly caught in the traffic, walking up to the protesters and open firing, leaving two men dead.
According to the Panama TV network TVN, who reported they were able to access the court hearing on the shooting incident for a few minutes, the suspect uttered something along the lines of “this ends here” before leaving his vehicle and storming up the highway towards the protesters.
The widely circulated video footage shows Mr Darlington arguing with a group of men from the protest.
He allegedly asked who the leaders of the campaigners were, to which the men replied that there were none.
“I don’t want to talk to women. I want to talk to men,” he responded, according to TVN.
While he was still confronting the protesters,