An exchange of gunfire took place Saturday on the border between Iran and Afghanistan, as tensions over water rights between the two nations escalate.

According to Iran's state-run news agency, IRNA, the Iranian forces inflicted "heavy casualties and serious damage" along the border of Sistan and Baluchestan province in the southeast and Afghanistan’s Nimroz province.

While IRNA stopped short of identifying those the Iranian border guards fired at, the IRGC-affiliated Tasnim News agency quoted Sistan-Baluchistan Border Guard Information Center as saying that the conflict was between the border guards and “unknown armed forces who intended to cross the border illegally.”

According to the AP, Afghanistan's Taliban-controlled media did not acknowledge the fighting, but Tasnim quoted some Afghan local media as saying that the conflict took place in Kang district of Nimroz province between Taliban regime forces and the Iranian border guards.

Tasnim also quoted its field correspondent as reporting that there was also a clash between the Iranian border guards at Nimroz and Taliban forces stationed on the Afghan side.

“With the cessation of the conflict, the border guards of Iran and the Taliban have already convened a meeting to investigate the causes of the tension,” added Tasnim. However, it is not clear if the fighting stopped later on Saturday.

“Small and semi-small weapons and artillery have been used in this conflict, however, the reports that Iranian forces have used missiles is completely false,” claimed Tasnim.

The were also some reports that Zaranj airport in Nimroz was targeted by Iranian forces, however Tasnim rejected it.

Disputes between Tehran and Kabul have risen over the Taliban’s obstruction of Iran's access to Helmand River water in violation of a 1973 treaty.