One journalist was among the killed as the office of Sada-e-Afghan, a local news agency, is also located in the targeted building.
The initial findings showed that 40 people were killed and over 20 others injured in Thursday morning's terrorist attacks against Tebyan Social and Cultural Center in Dasht-i-Barchi locality of the western part of Kabul, an official told Xinhua anonymously.
The Kabul police and health authorities were collecting more information and the number of casualties may rise, he said.
Najib Danish, spokesman of Interior Ministry, told Xinhua earlier that 13 people were killed and 21 were injured in the serial blasts, adding the figures were likely to change.
Earlier, conflicting numbers about the casualties were reported by officials and local media reports.
A meeting was underway before the blasts in the populated area. Unofficial sources said more than 100 people were affected in the incident.
No group has claimed responsibility for the attacks in the area, which is mostly dominated by Shiite Muslims.
KABUL, Dec. 28 (Xinhua) -- At least 40 people were killed and more than 20 others injured after a twin suicide attacks and an ensuing bomb blast rocked a cultural center in the western neighborhood of Afghan capital of Kabul Thursday, authorities said.