QUETTA, Pakistan (AP) — Iranian border guards opened fire at a vehicle carrying a group of Pakistanis, killing four people and wounding two others in a remote area in the southwest, Pakistani officials said Thursday.

The incident happened near the border village of Mashkel in Baluchistan province on Wednesday, local police said. Government administrator Sahibzada Asfand said it was unclear why the Iranian forces opened fire.

Local police say the bodies of the four men had been handed over to their families.

There was no immediate comment from Tehran or Pakistan’s Foreign Ministry.

Security forces on both sides often arrest smugglers and insurgents who operate in the region. Pakistan in tit-for-tat strikes in January targeted alleged militant hideouts inside Iran, killing at least nine people in retaliation for a similar attack by Iran.