The Islamic State (IS) extremist group has claimed responsibility for the killing of four foreign cyclists who were attacked by at least one assailant with a gun and knife after being run down by a vehicle in southern Tajikistan.

The group's Amaq news agency published the claim on July 30, but did not provide details or evidence to back up its statement, which was also published by the SITE intelligence group.

The attackers “were soldiers of the Islamic State and carried out the attack in response to calls to target the citizens of the coalition countries,” a statement by the group said.

There are no previously known terrorist attacks on foreigners in Tajikistan.

Earlier on July 30, Interior Minister Ramazon Rahimzoda said in Dushanbe that a governmental group had been formed to investigate the incident, in which two Americans, one Dutchman, and a Swiss citizen were killed.

Three other foreigners -- including one French citizen -- were injured in the July 29 incident, in the Danghara district of the Khatlon region, about 150 kilometers south of the capital.

Authorities said at least one person had been detained in connection with the attack and one other was killed in a confrontation with security forces. That contradicted earlier reports suggesting two suspects had been killed and several more detained.

Three young men were named by police and are being sought in connection with the attack.

"The driver and passengers of a car that hit the foreign tourists, [then] got out of the car and attacked [the cyclists] with firearms and knives," Rahimzoda said.

Officials are exploring "all possible" motives, he added, "including a terrorist act."

Three of the cyclists were pronounced dead at the scene, while a fourth died in the hospital.

Khatlon health officials said the bodies of the dead tourists showed knife wounds.

Police said they believe a car found in the nearby village of Torbulok was the vehicle used to run down the cyclists.

Presidential Probe

Eyewitnesses told RFE/RL's Tajik Service that the incident did not appear to be an accident. One local resident who was at the scene of the incident shortly after it occurred said one of the injured cyclists told him that people jumped out of the car after hitting the cyclists and started stabbing them.

The U.S. Embassy to Tajikistan issued a statement saying that "according to multiple sources, on July 29 Tajik citizens hit seven foreign cyclists with their vehicle, exited the car, and stabbed the cyclists with knives."

The statement said that "the Ministry of Internal Affairs has detained one suspect and killed at least three other suspects."

"We condemn the senseless attack, offer our deepest condolences to the families of the victims, and wish the injured a speedy recovery," the statement adds.

The dead and injured cyclists were reportedly spread out over a considerable area, indicating that some may have been chased.

The U.S. Embassy said in its statement that it had "no evidence that indicates a heightened level of threat to U.S. citizens. We encourage U.S. citizens to maintain awareness of their surroundings."

The Dutch Foreign Ministry said the Dutchman who was killed was 56 years old and the other Dutch citizen injured in the attack was 58 years old.

Rahimzoda said the investigation was being put under the personal control of Tajik President Emomali Rahmon, whose country has recently sought to boost its foreign tourism.

Rahmon described the incident as a "cruel act" in a message of condolence to U.S. President Donald Trump.

'Very Worrisome'

Like several of its Central Asian neighbors, Tajikistan has battled extremism, and hundreds of Tajiks are believed to have left the country to join Islamic State in the Middle East or elsewhere.

Hidajet Biscevic, the EU ambassador to Tajikistan, told RFE/RL that he was "really shocked" by the incident, which he said was "very complex" and "very worrisome."

"People tend to believe that this is not an isolated attack done by these four, five, whatever number, young people in the Danghara region," he said. "[This incident] could also have a very strong psychological and social impact on the security of foreigners in the country at the time when Tajikistan is focusing its attention to attract foreign investment and foreign assistance for the development of the country, in particular in the area of tourism."

Biscevic said on July 30 that an extraordinary meeting of EU member state ambassadors in Tajikistan along with U.S. officials would be held later that day in Dushanbe, and he did not rule out that someone might propose sending security experts to Tajikistan to assist in the investigation.

The disappearance of a former special-forces commander to join IS in Syria in 2015 embarrassed Tajikistan, the poorest of the five former Soviet republics in Central Asia. The government has used appearances by returning former IS sympathizers and other public-relations efforts to discourage extremists' recruitment of Tajiks.

A report by The Hague-based International Center for Counter-Terrorism (ICCT) noted that Tajiks carried out the highest number of suicide operations by foreigners in Iraq and Syria during a stretch in 2016 among cases in which the attackers' country of origin was identified.