During the period 1970 to 1990 specially on Dec 30, a night before Halloween.
Explanation:
Devil night, a night before Halloween, mischievous youths engaged in acts of vandalism and arson damaging the properties as a part of pranks in Detroit, Michigan.
To stop the acts of arson, Angels' night was started to keep a check on the neighborhood between Nov. 29 - 31 by city volunteers. They informed the cases of fires or suspicious activities immediately and the culprits were held.
