Two Americans were among four cyclists killed Sunday by a hit-and-run driver in Tajikistan, authorities said.
Tajikistan's Interior Minister Ramazon Rakhimzoda said police were "looking at all versions, that includes accident, murder, any other version".
Two of the suspected attackers died during their arrests and four others were detained, the ministry said. Another suspect was detained and three remained at large July 30.
Swiss Foreign Ministry spokeswoman Silvia Mueller said that while the circumstances of the crash were unclear, the Swiss government's travel advice for Tajikistan notes there is a risk of attacks and poor road travel conditions in the Central Asian country.
In a statement published Monday, IS said that a "detachment from the soldiers of the Caliphate" had carried out the attack against "citizens of Crusader coalition countries", according to intelligence monitor SITE.
The video, released by RFE/RL's Tajik Service, shows a black sedan swerving to run down people spread across a rural road.
Tajik authorities did not say what the motive was for the attack. Tajikistan's interior minister said that, after striking the cyclists, the people in the vehicle got out and attacked them with a firearm and a knife. Three others were injured.
If ISIS's claims on the Tajikistan incident are confirmed, it would the first time Americans have been killed in a terrorist attack outside of the US since August 2017 in Barcelona, according to ABC.
"We can't say if it is an act of terror", Rahimzoda said earlier on Monday. "At this point, we can not say with confidence that a terrorist act or some other crime has been committed".
The Government of Tajik President Imomali Rakhmon - who expressed condolences to the US, Swiss and Dutch authorities on Monday - fought Islamist guerrillas in a 1992-1997 civil war that claimed tens of thousands of lives.