Close to 20 Indian soldiers were killed in a clash with Chinese forces in the disputed Himalayan border area, Indian official say. The incident occurs amid rising tensions making it the first deadly clash in the Himalayan border area in at least 45 years. However, both sides insist no single shot was fired as part of a longstanding pact. In the late-night clash, soldiers reportedly brawled with sticks, bats and bamboo sticks studded with nails. It is still unclear how a clash that did not involve any exchange of fire could prove so lethal.

India’s army said both sides suffered casualties with their statement noting that injured soldiers were “exposed to sub-zero temperatures in the high altitude terrain.” China also confirmed the incident but did not give further details. Instead, they accused India of crossing the border onto the Chinese side. Zhao Lijan, Chinese Foreign Ministry spokesman said India had crossed the border twice on Monday, “provoking and attacking Chinese personnel.

The two of the world’s largest armies have fought one war so far in 1962. In May, dozens of Chinese and Indian soldiers exchanged physical blows at the border in the North Eastern state of Sikkim. In 2017, the two countries also clashed in the region when China tried to extend a border road through a disputed plateau. Despite there being several reasons for the growing tensions, both sides still blame each other.

India has built a new road in what experts believe to be the most remote and vulnerable area along the LAC in Ladakh. India’s decision to revamp infrastructure seems to have infuriated Beijing considering the road could enhance Delhi’s capability to move men and equipment rapidly in case of a conflict. The two nuclear armed neighbors have a history of overlapping territorial claims and face-offs along the 2,100 mile Line of Actual Control separating them. However, no bullets have been fired in four decades despite border patrols bumping into each other resulting in occasional scuffles. This explains why Sunday’s night clash took many by surprise.