"The motorbike rider carrying a bag (of explosives) tried to cross the check post at Khilgaon (area) defying signals, forcing our men to fire gunshots that killed him instantly," a RAB official told PTI.
RAB's operations officer ASM Shakhawat Hossain said two personnel of the force at the check post were injured.
He said the bomb disposal experts found explosives in the bag carried by the suspected militant. An investigations was launched into the incident which appeared to be an abortive attempt of attack by the Islamist militants, he said.
The blast wounded two RAB men who were being treated at the nearby Combined Military Hospital in Dhaka Cantonment.
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It was the first attack ISIS had claimed in Bangladesh this year and 27th since September 2015.
Authorities issued a nationwide alert for all international and domestic airports and prisons in the country and ordered to step up security after yesterday's attack.
Bangladesh, however, ruled out the ISIS claim, calling it an act by homegrown militants, reiterating that there was no presence of any foreign terrorist group in the country.
Bangladesh has witnessed a nationwide anti-Islamist crackdown since last week while police said they arrested over 80 militants.