Hospital officials confirmed the casualty numbers. The officials spoke on condition of anonymity because they were not authorized to speak to the media.
Justice Ministry employees had moved to this facility after a 2009 attack on the nearby Ministry of Justice, which is now being repaired. That attack was part of a double car bombing which killed at least 147 people and heavily damaged the building.
Thursday's attack took place about a kilometer (two-thirds of a mile) away from the heavily fortified Green Zone, which houses several foreign embassies and Iraqi government offices.
Violence in Iraq has subsided from its peak in 2006 and 2007, but deadly attacks remain frequent a decade after the U.S.-led invasion of March 20, 2003.
Iraq's government is being challenged by weekly protests that began in December from Sunnis angry over perceived discrimination. The demonstrations have been largely peaceful, and most Iraqi Sunnis do not voice support for al-Qaida.
But al-Qaida hopes to exploit the increasing tensions. It believes Shiites are heretics and that Iraq's government is too closely allied with neighboring Shiite powerhouse Iran.
Earlier this week, al-Qaida claimed responsibility for the deaths of 51 Syrian soldiers and nine Iraqis in a well-planned assault in western Iraq on March 4, intensifying concerns that the terror group is coordinating with Islamist rebels fighting to topple Syrian President Bashar Assad.