The boom was reportedly heard in Adhamiya, a district in Baghdad about 4 miles north of the heavily fortified Green Zone housing the US embassy campus, according to Al-Arabiya.
The incident happened at the offices of Takadum, the political party of Mohammed al-Halbousi, the speaker of the Iraqi parliament. A day prior, a hand grenade was reportedly thrown at the building.
Video taken of the building's exterior shows broken glass and wood strewn about the area, but two motorcycles still standing upright.
Last week, Halbousi won re-election to a second term as speaker, following recent national elections in which Takadum came in second place. However, the vote was marred by intense factional disputes and a grouping of Shiite parties abstained from the vote.
Emergency crews were reportedly rushing to the scene.
Earlier in the night, the skies over Baghdad were lit up by US air defenses as a C-RAM system intercepted two rockets targeting the US embassy. Officially, no damage was caused by the incident, but video posted on social media showed one of the rockets falling on a school and exploding.