VIDEO: Motorist asks 'You want to be first?' before shooting dead two environmental activists blocking copper mine road in Panama

A 77-year-old man has shot dead two environmental activists blocking a road in protest against a copper mine deal in Panama.

Video of the incident shows the shooter, named locally as Kenneth Franklin Darlington Salas, remonstrating with protesters on the Pan-American Highway, 51 miles from Panama City.

Salas appears to remove some tyres blocking the road when one the protesters, according to witnesses, shouted: “Are you going to kill someone?” Salas is said to have replied: “You want to be the first?”

Moments later he lifts a gun and shoots the first demonstrator and then a second man who approached him. Witnesses say Salas then removed tree trunks on the road.

Mr Salas appears to remove some tyres blocking the road

Local media identified the victims as Abdiel Diaz, a teacher and union activist, and Ivan Mendoza. Mr Salas, who is thought to be US-Panamanian and a former lawyer, was arrested.

The deaths have aggravated social tension that have welled up since anger over a lucrative mining contract spilled into wider discontent and demonstrations against the Government.

Thousands of Panamanians have taken to the streets in recent weeks over the mining contract signed with Canadian firm First Quantum Minerals FM.TO.

Mr Salas was arrested shortly after

Road blocks set up by protesters have caused up to $80m in daily losses to businesses, according to Panama's association of company executives, with schools closed nationwide for over a week and more than 150,000 medical appointments missed.

Officials have urged people to end the protests, though construction workers' and teachers' unions have vowed to continue taking to the streets until the First Quantum contract is annulled.

Teachers protested the deaths of the activists during a demonstration in Panama City

The new contract, agreed on Oct. 20, was signed into law by Panama's government, and provides First Quantum a 20-year mining right with an option to extend for another 20 years, in return for $375m in annual revenue to Panama.

While the government has said the new contract offers better terms than the previous one, protesters disagree.