17-year-old Md Israfil and 15-year-old Robeya Khatun were married about eight months ago
The law-enforcing agencies also blocked the street on Wednesday night, said Jotirmoy Sarker, additional deputy commissioner of Sylhet Metrpolitan Police.
A bomb disposal unit from RAB-9 joined the operation later.
A traffic police sergeant called for help after noticing the object on his motorcycle in the evening.