Iranian border guards have reportedly killed at least six Pakistanis after they illegally crossed the border between the two countries. At least two other Pakistanis were wounded in the shooting on Thursday.

The dead and wounded men, who have not been handed over to Pakistani authorities, were reportedly livestock traders. However, other reports claim they were members of the Pakhtun tribe who entered Iran illegally in search of jobs.

Pakistani officials said the incident occurred near the Zaran border which overlooks the Iranian market town of Chah Bahar. The area is a traditional route for informal trade between the two nations.

According to the Express Tribune newspaper, the Iranian border guards shot indiscriminately without issuing any kind of warning.

The newspaper also said that the wounded were taken to a state-run hospital for treatment of injuries, while the bodies of the deceased have been detained for proper identification and legal proceedings.

The victims of the shooting have yet to be identified.

It is unclear when the bodies will be returned to Pakistan.

The incident may have been revenge for what happened earlier in January when police in Pakistan arrested three Iranian border guards who apparently crossed the border and killed a Pakistani man they had been chasing by car. The Iranians were later deported back to Iran.

Iran has long planned to build a separation barrier along its border with Pakistan, in order to stem the flow of illegal immigrants and drug smuggling. Pakistan’s Foreign Ministry has held that it has no objection to the border fence, citing that Iran has every right to construct such a barrier.