Barnstable Police Sgt. Michael Riley said a wall fell during the work and the Vietnam era smoke canister rolled out causing the residents to call the police.
Barnstable Police Sgt. Michael Damery, the departments training coordinator and a commander of the Cape Cod Regional SWAT team, arrived on scene and recognized the device.
“If you pull the pin, it will release red smoke,” Riley said.
Police brought the device back to the station, where it will eventually be turned over to the state police for destruction.
Riley said these calls are not unusual and normally happen when people are cleaning out the homes of older relatives.
If residents find any type of military ordinance, Riley says they should not be touched or moved and to call the police.
Police do not want any devices brought to the police or fire station.