Two migrants were shot dead on a road in Serbia near the village of Dobrinci, around 45 km (28 miles) northwest of the capital Belgrade, police said on Wednesday, giving no details of their deaths or identity.
Hundreds of thousands of migrants passed through the so-called 'Balkan route' from the Middle East, Africa and Asia passed on their way to the West in 2015 but it was shut in 2016 when Turkey agreed to stem the flow of people in return for EU aid and a promise of visa-free travel for its own citizens.
Migrants still arrive in Serbia, however, mainly from Turkey, via neighbouring Bulgaria. Frequently they use smuggling networks.
There are as many as 3,600 migrants in government-operated camps in Serbia, officials say.
Rights activists say hundreds of others are scattered in Belgrade and towns along the borders of Bosnia, Croatia and Hungary as they try to enter the European Union.
Serbian authorities have arrested dozens of people smugglers but incidence of violence involving migrants are rare.