ADEN, (AFP) – Gunmen killed three members of Yemen’s security forces in an attack on a checkpoint in the southern town of Zinjibar on Thursday, witnesses and a hospital official said.

Three masked men attacked the security forces near the town’s intelligence headquarters, killing two and wounding a third, witnesses said. The wounded man apparently died of his injuries.

An official at Al-Razi hospital in Jaar, just north of Zinjibar, said the bodies of three security forces members were brought in, all of whom had been shot in the head.

The assailants rode a motorcycle, one of them carrying a Kalashnikov assault rifle in a black bag, a security official said. Security forces were in hot pursuit of the attackers.

South Yemen, where many residents complain of discrimination by the Sanaa government in the allocation of resources, is the site of frequent protests and periodic unrest.

The south was independent from 1967 until 1990 when it united with the north. It seceded in 1994, sparking a short-lived conflict which ended with the south overrun by northern troops.