Islamic State is claiming responsibility for a deadly attack on Western bicyclists Sunday in Tajikistan, according to the SITE Intelligence Group.
Four cyclists, including two Americans, were killed south of Dushanbe when they were run down by a car. Several men then jumped out of the vehicle and stabbed their victims.
A Swiss and a Dutch citizen were also killed and three other cyclists were injured, including a tourist from France.
The Tajik interior ministry said police pursued and killed four of the attackers and arrested one. Other reports say two suspects are dead.
The Islamic State claim said its "soldiers" struck "citizens of coalition crusader countries" and that the next attacks will be more "devastating and bitter."
The claim was picked up by SITE monitors. But Tajik Interior Minister Ramazon Rahimzoda said authorities have not determined definitively if it was a terrorist act or a robbery.
"We condemn the senseless attack, offer our deepest condolences to the families of the victims, and wish the injured a speedy recovery," a statement from the U.S. embassy in Dushanbe said.
Diplomats also commend Tajik authorities for what they call their professional and quick response.
The embassy said as of Monday, it does not believe there is a heightened threat to U.S. citizens in Tajikistan.
Shortly after gaining independence from the former Soviet Union, the Tajik government fought a civil war against opposition forces that included many Islamists.
A large number of former Islamic fighters turned to extremism when the government later outlawed their political party.