The two other tourists killed were from the Netherlands and Switzerland. "The version of a terrorist act is also not being excluded", interior minister Ramazon Rakhimzoda told journalists on Monday. Authorities have also arrested a third suspect and recovered a damaged vehicle they believe was involved in the case.
According to Radio Free Europe, the Tajikistan Interior Ministry said three cyclists were declared dead at the scene and a fourth died later at a hospital.
The "Islamic State" later claimed responsibility for the incident in a release through its AMAQ news agency. An Interior Ministry official indicated at a press conference on July 30 that the collision may have been intentional and that at least one of the suspects attacked the travelers with a sharp object.
Rakhimzoda said one suspect was killed while resisting arrest, his ministry said two suspects were killed and the U.S. Embassy reported three.
A "wanted" notice disseminated by Tajik authorities named two suspects aged 18 and 19 from the same village close to the Tajik-Afghan border, and a third one, 21, from the town of Nurek located not far from the site of the attack. The department said it could not provide more information about the US citizens due to "privacy concerns", but that USA officials were working closely with Tajik authorities.
"We strongly condemn the cruelty of the attackers and recognise that they in no way represent the kindness and hospitality of the Tajik people", it said in a statement. 3 more, from Switzerland, the Netherlands and France, were injured - one of whom was also stabbed.
The British embassy in Tajikistan updated its regular travel advice for tourists following the incident.
Tajik President Emomali Rahmon extended condolences to U.S. President Donald Trump, Swiss President Alain Berset, and King of the Netherlands Willem-Alexander.
Thousands of people from Central Asia have joined Islamic State militants in recent years.