Cleanup of a collapsed building in Fort Greene began Monday as investigators try to figure out what caused it to crumble.

The four-story building on Myrtle Avenue that housed a bar and apartments collapsed Sunday, leaving four people with minor injuries and leading to the evacuation of six adjacent buildings.

Crews began removing the scaffolding that was up around the building before it came crashing down.

According to records, the 493 Myrtle Ave. building was cited by the Department of Buildings last month for a large crack that ran from the first to the third floor. The Department of Buildings has sent inspectors to the scene.

The department?s commissioner says 491 Myrtle Ave., which sits adjacent to the collapsed building, will have to be demolished.