Bolivia's president is following events at home while at an Americas summit
Two members of a mercenary gang said to have plotted to kill Bolivian President Evo Morales were veterans of the Balkan wars of the 1990s, reports say.
Three died and two were arrested in the eastern city of Santa Cruz after police fought a gunbattle with the group.
Bolivian police officials said two of the five fought for Croatian independence. The three others are said to be Irish, Romanian and Hungarian.
They were said to be planning attacks on government and opposition figures.
Chief among the suspected targets was Bolivian President Evo Morales, but Vice-President Alvaro Garcia Linera and Santa Cruz Governor Ruben Costas, a bitter opponent of Mr Morales, were also targeted, police said.
There has been no immediate explanation of why the alleged plotters would target government and opposition targets alike.
Mr Costas has questioned the government's information, accusing it of "mounting a show" aimed at discrediting the opposition.
Revealing details of the alleged mercenary gang, police chief Victor Hugo Escobar said prosecutors were now seeking "clear and concrete information".
The group, suspected by authorities of being behind a dynamite attack on the home of a Catholic cardinal earlier in the week, was tracked down on Thursday to a hotel in Santa Cruz, some 900km (620 miles) east of the capital, La Paz.
The resulting shootout killed Arpad Magyarosi, a Romanian, and Irishman Michael Martin Dwyer, officials say.
The police chief named Eduardo Rosa Flores, 49, a Bolivian-Hungarian man also killed in the gun battle, as the ringleader of the group.
He fought in the war for Croatian independence in the 1990s where he commanded a paramilitary organisation, reports said.
The two men arrested were named as Mario Francisco Tasik Astorga, 58, another veteran of the Croatian war, and Elot Toaso, a Hungarian computer expert.
Mr Morales revealed the existence of the alleged plot as he travelled to Venezuela and Trinidad for regional summits.
He said intelligence reports had warned of an assassination plot by a group comprising foreign attackers intending to "riddle us with bullets".
Early reports from Bolivia's leftist government suggested the plotters were linked in some way to opposition movements in the country's lowlands supported by Mr Costas.
But news that Mr Costas was himself thought to be a target brought a clarification from government officials.
"The terrorist group has a strategy... not only against the president or vice-president, but other authorities as well," Deputy Interior Minister Marcos Farfan told Bolivian radio.