A patient fled from his house in Bagachra area of Sharsha upazila after a test report confirmed his coronavirus infection on Thursday.
The 50-year-old man is a night guard of Bagachra area, according to UNB.
The man along with two other residents of the upazila including officials of Palli Bidyut Samity tested positive for Covid-19, said Dr Yusuf Ali, Health Officer of the Upazila.
Their houses were kept under lockdown as per the rule, Dr Yusuf said.
Bagachra Sub-Health Center Deputy Assistant Medical Officer Dr Motiar Rahman said he went to the patient's house to put it under the lockdown at 2:30pm but his house was locked.
Neighbours said he fled after he came to know about his infection.
Meanwhile, the number of confirmed coronavirus cases in Bangladesh crossed the 100,000-mark on Thursday after the health authorities announced detection of 3,803 new cases in the last 24 hours.
In the last 24 hours, 38 more patients succumbed to the disease, raising the death toll to 1,343.