Iranian military forces shelled a Kurdish village in northern Iraq on Monday, leaving three wounded and displacing hundreds of villagers in the area, the Voice of America reports.

The Iranians were targeting Kurdish rebel groups which lie closely along the border between Iraq and Iran. Kurdish sources said that one villager and two rebels were injured from the Haji Omaran region.

“The shelling started at 5 a.m. [local time] and continued for several hours, forcing hundreds of civilians from nearby villages to flee their homes,” Farzang Ahmad, the local administrator of the Haji Omaran sub-district in Iraqi Kurdistan, told VOA.

Iran accuses the Democratic Party of Iranian Kurdistan (KDPI) and Komala, both Kurdish leftist militant groups, of conducting guerrilla attacks on government units in Iran. The groups have fought a low-level insurgency against the Iranian government for decades. They now reside in Iraqi Kurdistan after being expelled from Iranian territory. Millions of Kurds live in Iran, with groups like the KDPI seeking to establish political autonomy in Iran similar to that in Iraqi Kurdistan.

The shelling was assumed to be in response to escalating violence between Iranian border guards and the Kurdish groups. An Iranian commander was killed and two border guards wounded in Kermanshah Province, Iran, on Saturday, according to Iraqi Kurdistan officials.

Artillery attacks like the one this week are not wholly unusual for the area. Last June, a similar attack wounded five civilians near the border, according to Kurdish sources.

The uptick in violence has been associated with the KDPI ending a ceasefire it had maintained for decades with the Iranian government in 2015, saying it would send fighters across the border back into Iran, but would fight only in self-defense. The Komala group had three of its fighters killed inside Iran last month, vowing to avenge their deaths as part of a renewed armed struggle.

Video reportedly showing images of the shelling was posted on Twitter accounts linked to the KDPI and Komala.