Unknown gunmen on Friday killed three Iranian border guards near the country’s northwestern border with Turkey, Iran’s state media reported.

The official IRNA news agency said the three were killed in a clash when “terrorists” tried to sneak into Iran’s West Azerbaijan province, located about 650 kilometers (400 miles) northwest of the capital, Tehran.

The report said two other border guard were wounded and that the infiltrators suffered heavy casualties. The province of West Azerbaijan borders both Iraq and Turkey and the report did not say which country the infiltrators had come from.