Residents say the area enjoyed relative peace until a fortnight ago when the armed gang started terrorising them.
Recent incidents have left a trail of victims nursing serious injuries at Msambweni Referral Hospital, where they recounted harrowing experiences with the gangs.
Mghendi is a founder of the Madvocate initiative where he helps recovery drug addicts, reformed criminals and teen moms with psychosocial support.
Chairman Samuel Kobia singled out the coastal region as worst affected by gangs that have terrorised residents and left them fearful.
Gunmen attacked the villages of Gora, Madomawa and Jambuzu and that 38 men and 67 women and children were missing.
Largely rural Shiroro, where the incident took place, is frequently attacked by armed gangs targeting villages and security personnel.