YANGON, Myanmar (AP) — Myanmar's army fired artillery shells into the heart of a town used by ethnic Kachin guerrillas as their headquarters on Monday, killing three civilians and wounding four others in the latest escalation of the conflict, the rebels said.

The deaths, which included a 15-year-old boy, were the first war casualties reported in the town of Laiza since the two sides resumed fighting in mid-2011 after nearly two decades of peace.

Laiza, located on Myanmar's northeastern border with China, has been attacked with artillery several times since last month, when the military launched an unprecedented wave of helicopter and jet fighter assaults on rebel positions in nearby hills.

Artillery rockets have hit Laiza twice in recent weeks, according to rebel officials, but the earlier strikes caused no casualties and no significant damage.

A member of the rebel Kachin Independence Army, who declined to be identified because he is not the group's official spokesman, said three shells struck the town center early Monday. One fell near four men who were warming themselves beside a bonfire, killing one on the spot, while another landed on a house, killing a 15-year-old boy, said the rebel, who visited both impact sites.

He said two children were among those wounded in the attack.

There was no immediate government comment.

The Kachin, like Myanmar's other ethnic minorities, have long sought greater autonomy from the central government. They are the only major ethnic rebel group that has not reached a truce with President Thein Sein's administration, which came to power nearly two years ago after almost five decades of military rule and has embarked on a wave of widely praised political and economic reforms.

A long-held truce broke down in June 2011 after the rebels refused to abandon a strategic base near a hydropower plant the government was building in a joint venture with a Chinese company. Since then, around 100,000 Kachin have fled their homes, and many are in camps near Laiza.

Last month, sporadic skirmishes escalated when the rebels rejected a government demand that they allow supply convoys to reach an army base. The Kachin had been attacking army units headed there, saying they were transporting ammunition that could be used to try to take Laiza.

The government denies it has designs on the frontier town, but has seized at least one of the guerrillas' hilltop posts by the road. Continued...