Authorities on Sunday blamed a slashing rampage that killed 29 people and wounded 143 at a train station in southern China on Xinjiang separatists, rounding up members of the city’s small Muslim Uighur community for questioning.

Police fatally shot four of the assailants — putting the overall death toll at 33 — and captured another after the attack late Saturday in Kunming, the capital of Yunnan province, the state-run Xinhua News Agency said. But authorities were searching for at least five more of the black-clad attackers.

State broadcaster CCTV said that two of the assailants were women and that one had been slain and the other detained.

“All-out efforts should be made to treat the injured people, severely punish terrorists according to the law and prevent the occurrence of similar cases,” said China’s top police official, Politburo member Meng Jianzhu, who arrived in Kunming early Sunday, an indication of how seriously authorities view the attack.

The U.N. Security Council on Sunday issued a news release that “condemned in the strongest terms the terrorist attack” on the train station. The statement reiterated that “any acts of terrorism are criminal and unjustifiable regardless of their motivation” and underlined the need to bring those responsible for the attack to justice.

The attackers’ identities have not been confirmed, but Xinhua said evidence at the scene showed that it was “a terrorist attack carried out by Xinjiang separatist forces.”

The far western region of Xinjiang is home to a simmering rebellion against Chinese rule by some members of the Uighur population, and the government has responded with heavy-handed security there.

Conflicts in the region have resulted in hundreds of deaths, but most of the violence has been contained to Xinjiang.

Sean Roberts, a cultural anthropologist at George Washington University who has studied Uighurs and China for two decades, said the Kunming violence, more than 900 miles from Xinjiang, would be a new kind of attack for ethnic Uighurs: premeditated, well-organized and outside the disputed territory.

“If it is true that it was carried out by Uighurs, it’s much different than anything we’ve seen to date,” Roberts said by phone.

But he added that it is still unclear whether there is any organized Uighur militant group and said that the recent attacks do not appear to be linked to any “global terrorist network, because we’re not seeing things like sophisticated explosives or essentially sophisticated tactics.”