Burmese soldiers have killed at least four men during a sweep of Muslim villages following deadly attacks on police posts along the northwestern border with Bangladesh, state media said on Tuesday.

The violence, the most deadly in northern Arakan State since communal clashes in 2012, represents a key challenge for the government of democracy figure Aung San Suu Kyi, who has urged authorities to use caution to avoid inflaming tension.

Troops “providing security for residents” recovered four bodies after clashing on Monday with residents of Myothugyi, a village of about 1,000 Muslim homes in Maungdaw Township, state-run media said, but other accounts suggest the toll could rise.

“The troops came under surprise attack by around 20 armed attackers,” said a state-run newspaper, the Global New Light of Myanmar, adding that a homemade gun, three bullets and a knife had been discovered.

Military forces fanned out in the area, home mostly to stateless Rohingyas, whose movements are tightly controlled, after nine border police were killed and five injured in three apparently coordinated attacks on Sunday.

Husein Juha, a Muslim administrator in Myothugyi, put the number of dead in Monday’s incident at seven.

“They shot them because they were running outside the village. They didn’t stop running when soldiers asked,” said Juha, 32, adding that fear of the soldiers had prompted some villagers to arm themselves with makeshift weapons.

The bloodshed in Myothugyi may have been replicated elsewhere, according to information gathered by international aid groups working in Arakan State and advocacy group the Arakan Project.

Reuters was unable to verify the information, however.

Schools and markets remain shut amid the military and police hunt for those behind Sunday’s attacks. Authorities have called a curfew in Maungdaw from 7pm to 6am, and barred gatherings of five or more.

In one of the attacks, officials say, 90 people, believed to be Rohingyas, targeted a border police headquarters and made off with more than 60 weapons and 10,000 rounds of ammunition.

Two Muslim men captured during Sunday’s attacks have reportedly confessed, Arakan State police Major Sein Lwin told Reuters.

The men, charged with murder, conspiracy to murder and the assault of civil servants, said the attacks had been planned by a single “leader,” Sein Lwin added.

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He declined to name the leader, but said he had ties to an unnamed armed group operating across the Bangladesh border, which Burma has closed, and where Bangladesh has stepped up patrols.

Nobel laureate Suu Kyi, who leads Burma‘s six-month-old civilian administration, has faced criticism for failing to tackle rights abuses against the Rohingya and other Muslims.

In August, she appointed former UN chief Kofi Annan to chair an advisory panel on Arakan State that visited the area for the first time in September, but has yet to go to the northern Muslim-majority townships.

The violence in 2012 killed more than 100 people and left about 125,000, mostly Rohingya, unable to return home.