Bogura, Pabna and Joypurhat districts confirmed four positive cases of coronavirus on Thursday.
All of their samples were tested at Rajshahi Medical College Hospital.
Bogura's Deputy Civil Surgeon Mostafijur Rahman confirmed the matter to The Business Standard.
The coronavirus patient of Bogura went to his home in the district's Adamdighi upazila from Dhaka riding a motorbike on April 8.
Bogura's Deputy Commissioner Forej Ahmed said the authorities have decided to lock down the upazila from Thursday night to curb the spread of the virus.
Our Pabna correspondent reports: The first coronavirus patient of Pabna have been identified in the district's Bamongram village under Chatmohor upazila.
The 32-year-old male came from Narayanganj on April 5, the district's Civil Surgeon Mehedi Iqbal said.
As he became sick and started showing symptoms of coronavirus, the authorities collected and sent his samples to Rajshahi for coronavirus test.
Authorities have locked down his village after the test results came positive.