Two workers and two firefighters were injured after a wall collapse at a Flatbush construction site Monday. Emergency workers on the scene say crews had to be called from as far away as Queens to help pull the workers from the site. The accident blocked off traffic from East 21st Street to East 23rd Street. A resident who lives next to the site says the vibration and thumping of the wall collapse was terrifying. Others say they heard the workers screaming as the wall came down. The fire department says the two workers were taken to the hospital in critical condition. The two firefighters were treated for minor injuries and released. There's no word yet on exactly what caused the wall to cave in. The construction site will be closed until further notice.