A Chinese government committee said Thursday that a rush to build schools during the country’s recent economic boom might have led to shoddy construction that resulted in the deaths of thousands of students during a devastating earthquake in May.

The statement by Ma Zongjin, the chairman of an official committee of experts assessing damage from the May 12 earthquake, is the first time that a representative of the Chinese government has acknowledged that poor construction may have led to the collapses. Until now, officials in Beijing and in southwest China’s Sichuan Province, which suffered the most damage, had said the sheer force of the 7.9-magnitude quake caused the collapses.

The school collapses have become the most politically sensitive issue to emerge in the aftermath of the earthquake. This summer, grieving parents held street protests to challenge local governments and demand that officials conduct proper investigations into construction quality.