BANGKOK (AP) — Myanmar ’s military-controlled government said Thursday that almost half of more than 250 cargo trucks stranded by fighting against ethnic minority armed groups near the northeastern border with China have been destroyed in a fire caused by bombs dropped by drones.

Maj. Gen. Zaw Min Tun, spokesperson of the ruling military council, said in a statement phoned to state television MRTV that trucks parked in a compound near a trade zone in Muse township caught fire after drones belonging to ethnic armed organizations launched an attack at about 9:45 a.m. on Thursday.

The action was one of the most dramatic, and in terms of property damage, most extensive since the self-styled Three Brotherhood Alliance of the Myanmar National Democratic Alliance Army, the Ta’ang National Liberation Army and the Arakan Army launched a coordinated offensive in northern Shan state on Oct. 27. The trucks are used to carry goods to and from China.

Zaw Min Tun said about 120 of 258 trucks, which were parked near the Kyin-San-Kyawt Border Gate, were destroyed in the fire, which he blamed on the alliance. He said the fire was put out after about six hours but made no mention of casualties.

Le Kyar Win, the spokesperson of the Myanmar National Democratic Alliance Army, denied the alliance carried out the attack, blaming the military itself.

“To be honest, this is an act that harms the people. And that place is not our military target. So there is no reason for us to attack,” Le Kyar Win said.

The alliance has claimed widespread victories, and the military government acknowledged soon after fighting began that it had lost three towns. The fighting has included destroying bridges and cutting key roads from Myanmar’s interior, Zaw Min Tun said. The fighting of the past three weeks appears to have stopped almost all legal cross-border trade with China, a major economic disruption for Myanmar.

It also has put pressure on the military government in its struggle against the armed pro-democracy forces that are challenging it in other parts of the country, where new attacks were carried out after the Oct. 27 offensive.

Armed resistance arose after the army seized power in February 2021 from the elected government of Aung San Suu Kyi and has tenaciously carried on against the military regime’s better-armed and more numerous security forces. The pro-democracy People’s Defense Force has joined hands with several of the well-organized, battle-hardened ethnic armed groups that have been fighting Myanmar’s central government for greater autonomy for decades.

“The escalation is now the largest in scale and most extensive geographically since the early 2021 military takeover, impacting multiple areas, particularly northern and southern Shan, Sagaing, Kayah, Rakhine, and southern Chin,” areas in northern, central, eastern and western Myanmar, said a situation report circulated Wednesday by the U.N. Office for the Coordination of Humanitarian Affairs, OCHA.

It also said that “key transport routes in townships with active fighting” had been blocked by both the army and the ethnic armed groups, “restricting people’s movements to safer locations, as well as hampering humanitarian access.”

The report by the U.N. agency said that 187 civilians have reportedly died and 246 others have been injured while more than 286,000 people have been displaced by the fighting that began late October. According to its estimates, more than 1.8 million people have been displaced since the army’s 2021 takeover.

The Myanmar National Democratic Alliance Army is besieging the town of Laukkaing, which is the administrative capital of what is officially called the Kokang Self-Administered Zone.

The Myanmar National Democratic Alliance Army is a military organization of the Kokang minority that is trying to oust a rival Kokang group backed by the military government from its seat of power in the town.

Laukkaing is notorious for hosting major organized criminal enterprises including cyber-scam operations controlled by Chinese investors in collusion with local Myanmar warlords.

Beijing is embarrassed by the large-scale criminality and has vowed to eradicate it. In recent weeks, as the Myanmar National Democratic Alliance Army has gained ground, thousands of Chinese nationals involved in such operations have been repatriated into police custody in China.