It wasn’t the kind of real estate collapse that many China observers have been warning about—but for dozens of residents of an apartment building that disintegrated in the eastern province of Zheijiang on Friday, it was much scarier.

The collapse of a five-story building in the city of Fenghua trapped at least six people, one of whom has died so far, according to state media (in Chinese). The apartment building was built in 1994—part of a nationwide boom in the 1980s and ‘90s that packed the Chinese real estate market with substandard, shoddily built buildings. Authorities are warning that the poor quality of buildings from the those decades could represent huge dangers in coming years.

“We mustn’t deny it—starting in the 1980s, to create enough homes for people, a lot cities resorted to building ‘fast food houses,’” Chen Xuwei, vice secretary of the Hangzhou Civil Engineering and Construction Association, told the state-owned news agency Xinhua. Fast food houses are easy to build but they’re not built well—after a few decades they may come crashing back down.

According to the Xinhua report, there have been a number of collapsed buildings in 2009, another in 2012, and two more in 2013—all were residential buildings constructed between 1980 and 2000.

As Quartz recently reported, a large percentage of Chinese housing stock is old and decrepit. The exact percentage, thought to be between 22% and 47%, makes a huge difference in determining whether the country is in the midst of a dangerous real estate bubble. But whether at the high end or the low end, that would still leave many millions of people living in dangerous buildings.