The attack took place yesterday when assailants in three cars blocked the vehicle, Igor Kalyapin, chairman of the Committee For Prevention of Torture and a member of the Russian Presidential Human Rights Council, said on the council's website.
Timur Rakhmatulin, the NGO's regional leader, told The Associated Press that two of the journalists and the bus's driver were hospitalised, but their conditions weren't immediately known.
The journalists on the trip included a reporter for Swedish state radio and one from Norway's Ny Tid newspaper, Rakhmatulin said. There were also reporters from major Russian broadsheet Kommersant, as well as Russia's New Times and Mediazona, he said.
"They yelled 'You're supporting terrorists, the killers of our fathers.' We laid on the floor but they began to scream for us to get out," he was quoted as saying.
The meaning of the attackers' words was not immediately clear. Chechnya, and Russia's North Caucasus is heavily Muslim, but divided between those who follow Kremlin-backed Chechen President Ramzan Kadyrov and adherents of extremist Islamists who lean toward groups such as the Islamic State in Syria and Iraq.