Pakistan said on Wednesday that two of its citizens were killed in firing by an Afghan border guard at a southwestern crossing.
The Pakistan Army said in a statement that an Afghan sentry opened "unprovoked" and "indiscriminate" fire on pedestrians going from Pakistan to Afghanistan at the Chaman border crossing, killing two civilians, including a 12-year-old boy.
The shooting also injured another child, the statement said.
Chaman, one of two key border crossings between the two neighbors, connects southwestern Balochistan province with Afghanistan's southern Kandahar province.
The incident was the latest in a series of border clashes between the two border forces in recent months, and it came on the heels of Pakistan's ultimatum to illegal Afghan refugees to leave the country by Nov. 1.
The Pakistan Army said its troops exercised "extreme" restraint and avoided any exchange of fire in the presence of innocent people in order to "avoid collateral damage."
Bodies and the injured were evacuated and shifted to a local hospital by the security forces.
"Afghan authorities have been approached to inquire the reason for such irresponsible and reckless act, apprehend and hand over the culprit to Pakistani authorities," the statement added.
Pakistan, it went on to say, continues to "contribute towards peace, prosperity, and development through positive and constructive bilateral relations; however, such unpleasant occurrences have the potential to harm the sincere intent and purpose."
Pakistan and Afghanistan share 18 crossing points-the most commonly used ones are Torkham and Chaman-along 2,640 kilometers (1,640 miles) long border.
There was no immediate reaction from Afghanistan. However, Pakistan and Afghanistan often accuse each other of initiating firing at the Chaman border crossing.