Police say the blast in the Ghadir district tore through the car of Anmar Taha Ridha, who works on the maintenance crew of Iraq's government headquarters. Ridha and his wife were injured and their three children -- aged six, eight and 10 -- were killed Thursday.

The police officials spoke on condition of anonymity because they were not authorized to speak to the media.

Hospital officials confirmed the death toll.

Elsewhere in Baghdad, friendly fire killed one policeman at a checkpoint near the Finance Ministry.

Police say guards opened fire after the police vehicle attempted to bypass the barricades.