Police shot and killed two ethnic Uygurs from Xinjiang who reportedly attacked them with knives late on Sunday in the Guangxi Zhuang autonomous region, officers said on Monday.

Five Uygurs were found by police in Pingxiang, a city in Guangxi that borders Vietnam, but they allegedly resisted arrest after trying to cross the border illegally and fought officers with knives.

Two of them were shot dead and the other three were captured, Guangxi police said.

According to the Ministry of Public Security, in recent years a number of young, violent suspects from the Xinjiang Uygur autonomous region and extremists have entered Southeast Asian countries illegally, including Vietnam and Thailand.

From there, they usually buy fake passports and travel to Turkey to join extremist organizations and receive military training, before returning to plan terror attacks, according to the ministry.

In April, the ministry launched a campaign to crack down on organized illegal immigration in China’s southern border regions, including the Xinjiang and Guangxi autonomous regions and Yunnan and Guangdong provinces, as the number of such cases has soared sharply since the start of last year.

According to the ministry, in 2013, police in Yunnan and Guangxi uncovered 100 cases of illegal immigration and captured 795 suspects, seven times more than in 2012.

Since April, police have uncovered 262 human smuggling cases and have captured 352 suspects who allegedly organized such activities and 852 who attempted to cross borders illegally.

Dong Xiaogang, deputy director of the ministry’s Criminal Investigation Bureau, said, “Xinjiang extremists have colluded with foreign accomplices to operate organized illegal immigration.

“Gang members assume different tasks to form a complete chain ... including organizing Xinjiang extremists, transportation, illegal immigration at borders and handling fake passports.”

The ministry said police will strengthen management and border patrols and also increase personnel in some key areas, including railway stations and other public areas with large flows of people.

They will also concentrate on combating those who help suspects to cross borders, Dong said.

Mei Jianming, director of the Counterterrorism Research Center at People’s Public Security University of China, said the key to ending terrorist acts is judicial cooperation with other countries.

Xinhua contributed to this story.