The wall fell at the construction site before 7:35 a.m. at 61 Dunster Road in Bedford, according to Bedford Police and Fire Departments. Five workers were taken to an area hospital, with one having life-threatening injuries.
A bystander administered life-saving aid until paramedics arrived and first responders were able to extricate the trapped people.
A Bedford firefighter was injured in the process and was treated on-scene.
The Bedford Building Inspector determined through an initial investigation that improper construction techniques were used, but OSHA will conduct a follow-up investigation and determine the final cause.
The workers were building on an addition to the home. The homeowners were not at the scene at the time of the collapse.
Click here to follow Daily Voice Lynn and receive free news updates.