DUSHANBE (Reuters) - Four Western cyclists were killed when a car plowed into them in Tajikistan in what may have been a terrorist act in which the attackers also stabbed their victims after injuring them, the interior minister and the U.S. embassy said on Monday.

The tourists, from the United States, Switzerland and the Netherlands, were killed in the Central Asian country on Sunday, the authorities said. Three others, from Switzerland, the Netherlands and France, were injured - one of them also from a stab wound.

Security forces pursuing suspects in the attack killed four, including one who resisted arrest, and detained a fifth man, the former Soviet republic’s interior ministry said.

“We are looking into all versions - accident, robbery ... including a terrorist act,” Interior Minister Ramazon Rakhimzoda told a briefing.

Among the four suspects killed was the owner of the car, which police believe hit the group as they cycled through a rural area 90 km (55 miles) southeast of the capital Dushanbe.

A purported video of the incident published online by Radio Free Europe and credited to an anonymous source showed a car doing a U-turn on a narrow road after it had already run into the group and then running over several of the cyclists.

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 U.S. Embassy said it could not name the two U.S. victims due to privacy concerns, but indicated that it also considered the incident to be an intentional attack.

“We strongly condemn the cruelty of the attackers and recognize that they in no way represent the kindness and hospitality of the Tajik people,” it said in a statement.

“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 embassy said in another statement issued later on Monday.

Still, the embassy said it had “no evidence that indicates a heightened level of threat to U.S. citizens”. It also commended the Tajik authorities “on their professional and quick response to the incident”.

Switzerland’s Foreign Ministry confirmed the death of one Swiss national and said it was in contact with the second tourist, who has been injured. “If it is established that this was a terrorist attack, it will be noted in future travel advice for Tajikistan,” the ministry said in a statement.

Britain’s Foreign Office urged UK tourists in Tajikistan, particularly those hiking or cycling in its south, “to exercise extreme caution and vigilance during their visit”, citing “the first incident of this kind in Tajikistan”.

The government of Tajik President Imomali Rakhmon - who expressed condolences to the U.S., Swiss and Dutch authorities on Monday - fought Islamist guerrillas in a 1992-1997 civil war which claimed tens of thousands of lives.

Some Tajik Islamists then joined a coalition government but in 2015 the state outlawed their political party, accusing its leaders of being behind a failed coup, a charge they deny.

Thousands of people from the mainly Muslim region have joined Islamic State militants in recent years. Several men from Central Asia were detained last year over a bombing of the metro in Russia’s St Petersburg, and over truck attacks in New York and Stockholm.