Police official Rahmat Ullah says Ananta Bijoy Das died instantly after the attack Tuesday in Sylhet city.
It was not immediately clear why he was targeted, but local media reported that he was close to Avijit Roy, a Bangladeshi-American blogger and writer who was killed in February, allegedly by Islamist extremists. Roy was known for his writings against religious fundamentalism.
Das's friend Shahiduzzamn Paplu told reporters that Das wrote blogs and books dealing with science, and that he also had written an introduction for a book by Roy.
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