At least eight people drowned after a boat carrying migrants overturned while crossing the Drina River from Serbia to Bosnia, officials in the two Balkan countries said Thursday.

Serbian police received a call around 5 a.m. from their counterparts in Bosnia and a citizen who reported the accident, said Interior Minister Ivica Dacic.

It was not immediately possible to confirm the exact number of people on the boat, with authorities providing different accounts.

Dacic said that 18 migrants, including three children, managed to cross into Bosnia, out of 25 people who were in the boat when it overturned.

"Police and rescuers are continuing a further search of the Drina River and the surrounding terrain," said Dacic in a statement.

Dacic said that out of 18 migrants who made it to shore, 16 are from Syria and two are from Egypt. They include 10 minors.

Bosnian emergency official Boris Trninic said earlier there were about 30 people in the boat, 15 of whom reached safety.

Migrants using the so-called Balkan land route in their efforts to reach Western Europe come to Serbia from Bulgaria or North Macedonia before moving on to Hungary, Croatia or Bosnia.

To reach wealthy European countries, people fleeing wars and poverty often turn to smugglers to take them across borders without authorization.