A member of the United People's Democratic Front (UPDF) was held along with arms at Dighinala upazila in Khagrachhari district on early Thursday.
The detained person was identified as Sunil Chakma Prakash Suvash, 27.
It was learned that when law enforcers signaled a motorcycle in Baghaichari Mukh area around 12:15 am to stop, Sunil got off the vehicle and tried to run away.
Later, police and army members chased after him and detained Sunil.
A pistol, a magazine, five rounds of bullet, Tk 17,635 in cash, and receipt book were recovered from his possession.
Dighinala Police Station officer in-charge (OC) Uttam Chandra Deb confirmed the matter.