– Chinese authorities have said late Monday that they had arrested three more suspects in Saturday’s deadly bloodbath in southern China, an attack they hinted earlier in the day was linked to international terrorist groups.

Both claims were difficult to verify, deepening the mystery of how a handful of assailants, armed with only knives and sabers, managed to kill 29 train commuters and injure more than 140 others.

Since news of the train station attack broke Saturday from the southern city of Kunming, the Chinese public has responded with both sympathy for the victims and calls for harsh retribution against those who carried out the attacks.

‘Whole new level’

As of late Monday, however, Chinese authorities had not made public the identities of four assailants initially killed, another one quickly captured or three others reported arrested on Monday. Nor have they detailed why Kunming police have linked the suspects to “separatists” in China’s far western Xinjiang region, where police and the local Muslim population — known as Uighurs — have clashed for years.

Dru Gladney, a professor at California’s Pomona College who specializes in Central Asia, said China has offered little evidence to back up a link to Xinjiang militants. If a link is confirmed, he said, it would represent a significant change in tactics and planning among Uighur militants, whose attacks generally have been aimed at Xinjiang police, not civilians in other parts of China.

“Assuming this is confirmed, it represents a whole new level of planning and complexity than what we have seen in the past,” Gladney said. “It really ups the ante.”

‘A despicable trend’

The Kunming attack follows a deadly Beijing incident in October, when three Uighurs drove a jeep into a crowd at Tiananmen Square, killing two and injuring 40 before setting the vehicle on fire, killing themselves. “The latest attacks in Beijing and Kunming have clearly indicated a despicable trend that separatists are targeting civilians out of Xinjiang,” said a commentary Sunday on the English-language website of the Global Times, a state-run newspaper.