(reuters) -- Around five assailants attacked the compound where police and army troops are based. One blew up his explosives vest at the entrance while the other four clashed with guards for around three hours, said army colonel Mohammed al-Assadi.

Police and army soldiers managed to kill the four attackers while six policemen and soldiers were also wounded, Assadi said.

ISIS's self-proclaimed caliphate effectively collapsed last month when U.S.-backed Iraqi forces completed the recapture of Mosul, the militants' capital in northern Iraq, after a nine-month campaign.

Some parts, including small towns and mountain areas, remain under ISIS control, especially along the border.