Abuja: In a pre-dawn attack, unknown assailants killed three South Korean doctors in Nigeria`s northern state of Robe, police said on Sunday.
Sanusi Rufai, the commissioner of police of Robe state, said the attack occurred in the town of Potiskum.
"They invaded the apartment of the doctors....And slit their throats," Rufai said.
Residents say the slain doctors worked at a general hospital in the city. No group has claimed responsibility for the attack.
Robe shares border with Borno state where terrorist group Boko Haram has its headquarters.
Last week, nine health workers on polio vaccination drive were shot dead by suspected Islamists in northern city of Kano.
Potiskum has witnessed repeated attacks by the group which has vowed to turn Nigeria into an Islamic state.
Boko Haram has a breakaway terrorist sect known as Ansaru which has attaced foreigners in the past.