Pakistan on Sunday detained three Iranian border guards after they allegedly crossed the border and shot at a car, killing a Pakistani national, local Pakistani officials said.
The Iranians reached Mazan Sar Mashkail, in Washuk district, three kilometres (1.8miles) inside Pakistan where they opened fire on a vehicle they were chasing, according to officials in Balochistan.
"All three personnel of Iranian border security force were taken into custody for their penetration inside Pakistan and killing a Pakistani national on our soil", Saeed Ahmad Jamali, Deputy Commissioner of Washuk district told AFP.
A Pakistani national was killed and his brother was wounded by gunshots in the incident, he added.
Mazan Sar Mashkail is around 600 kilometres southwest of Quetta, the main town of insurgency hit Baluchistan province, which borders Iran's Sistan-Baluchestan province.
Iranian embassy officials in Islamabad were unavailable for comment late Sunday but Iran in the past has blamed a Sunni extremist group, called Jundallah, for launching attacks inside Pakistan from Sistan-Balochistan.
Jundallah says it is fighting Tehran's Shiite rule to secure rights for Sunni Balochis who form a significant population in Sistan-Balochistan, which borders both Afghanistan and Pakistan.
Pakistani officials said the Iranian guards were trying to take both Pakistani nationals back into Iran.
"Both Pakistanis were injured and one was later died. Pakistani troops at the border surrounded the Iranians and have taken them into custody", Jamali added.
"We have contacted our senior officials about the fate of these Iranian, Jamali said.
A Pakistan security official in Quetta confirmed the incident with request of anonymity as he was not authorised to speak to media.