MOSCOW -- The Islamic State of Iraq and Syria (ISIS) has claimed responsibility for an attack in Tajikistan that left four cycle tourists, including two Americans, dead over the weekend. The terror group released a video later on Tuesday purportedly showing the five men who carried out the attack pledging allegiance to its leader Abu Bakr al-Baghdadi.

Tajik police earlier issued a statement blaming a banned Islamist political party for the attack, in which a driver allegedly rammed his car into the group of foreign cyclists and then joined his passengers in going after them with knives.

ISIS initially claimed responsibility for the attack in a generic statement late Monday, offering no proof of a connection, but on Tuesday the group disseminated the two-minute and 40 second video showing five young men sitting under a tree on a hilltop, speaking Tajik with Arabic subtitles, pledging allegiance to al-Baghdadi but saying nothing specific about any attack plot.

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Authorities in the ex-Soviet republic in Central Asia said Monday that they were considering an extremist plot among the possible motives for the attack.

A file photo shows a touring bicycle parked along the M41 Pamir Highway, in the Pamir Mountain Range of Tajikistan. iStockphoto

A Daewoo sedan plowed into the group of seven foreign bicyclists about 60 miles south of the Tajik capital, Dushanbe, on Sunday, according to local police. The people in the vehicle then "exited the car and stabbed the cyclists with knives," the U.S. Embassy in Tajikistan said in a statement Monday.

Four of the cyclists died and three others, including a woman from Switzerland, were injured, Tajik officials said.

Two of the victims were American, one was Swiss, and another was from the Netherlands, foreign and Tajik officials said. Tajik President Emomali Rahmon sent the leaders of each country a telegram expressing condolences Monday.

United States Charge dAffaires in Tajikistan, Kevin Covert, met people at the American embassy in Dushanbe who came to pay their tributes to the victims of the attack.

The United States Charge dAffaires, Kevin Covert (R) speaks with a man as people come to pay their tribute to the victims of a deadly attack, at the U.S. Embassy in Dushanbe, July 31, 2018. Getty

Earlier on Tuesday, citing what it said was the confession of a detained suspect, Tajikistan's interior ministry said the Sunday attack leader was trained in Iran and that the group had planned to flee to Afghanistan after the attack, according to the Reuters news agency. The Ministry blamed the Islamic Renaissance Party of Tajikistan (IRPT) for the attack. That group was banned in 2015, accused of plotting a coup.

The Interior Ministry, which oversees the police, said four suspects were killed and one taken into custody on Monday, and then four more people taken into custody for suspected links on Tuesday, according to Reuters.

Interior Minister Ramazon Rakhimzoda told reporters earlier that one of the survivors had knife wounds and police found knives and guns with some of the suspects. He described the car crash as "an attack," and said investigators were examining all possibilities, including a road accident, murder and terrorism.

The State Department issued a statement Monday condemning what it called a "senseless attack" and expressing "deepest condolences" to the families of the people killed. The department said it could not provide more information about the U.S. citizens due to "privacy concerns," but that U.S. officials were working closely with Tajik authorities.

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.

"Should it turn out to have been a terrorist act, this would be recorded in the travel advice," Mueller said.

The State Department encouraged Americans headed abroad to monitor government advisories for updated information on where it is safe to travel.