Four tourists, including two Americans, were killed in Tajikistan on Sunday by armed attackers in what was originally reported as a hit-and-run road accident, the interior minister said Monday.
"(The suspects) had knives and firearms," minister Ramazon Hamro Rahimzoda said of the attack that left tourists from the United States, Switzerland and the Netherlands dead and two others injured.
The dead were on a cycling tour in the impoverished ex-Soviet nation, in a group with three other tourists from Switzerland, the Netherlands and France.
"One tourist received a knife wound and is being given medical assistance. The victim's condition is stable," said Rahimzoda without mentioning nationality.
Another was being treated in hospital, while the French citizen survived without injury and was being questioned by the police, he added.
Two suspects in the case were killed after they "resisted arrest" and a further four have been detained, the minister said.
Police are also pursuing other suspects.
"We are considering all possibilities," Rahimzoda said of the criminal investigation.
"We can't say if it is an act of terror," he added.
However the minister said that "state institutions are being guarded...to provide safety for citizens and tourists".
Tajik President Emomali Rakhmon on Monday sent notes of condolence to the US, Switzerland and the Netherlands over the deaths.
The US embassy in Tajikistan confirmed two of the fatalities were US citizens, but did not disclose names.
The incident took place in the district of Danghara, 150 kilometres (90 miles) south of the capital Dushanbe.
Tajikistan is the poorest of the ex-Soviet republics and has been ruled by the iron hand of Rakhmon, 65, since 1992.