Seven women and five men were killed at a brother in the Baghdad on Tuesday, medical and security officials said Al Arabiya reported.
The attack took place at an apartment in the Zayouna area of east Baghdad. A similar attack took place in the same place last year.
Last May 22, gunmen killed 12 people in an attack on a house that was used as a brothel in the Zayouna area.
The week before, gunmen restrained police officers at a checkpoint in the same area, and shot dead 12 people at a row of adjoining alcohol shops nearby.
Violence in Iraq has reached a level not seen since 2008, when the country was just emerging from a brutal period of sectarian killings.
It took just five days for this month's death toll to surpass that for all of January last year.