Four trains are currently stranded at both ends of the Bangabandhu Bridge
The policeman has been identified as Atiqur Rahman, a nayek at Special Security and Protection Battalion or SPBn, which is tasked with providing security for the state's VVIPs.
He was taken to Dhaka Medical College Hospital around 12:30am on Saturday, said DMCH police camp Sub-Inspector Bachchu Mia.
The SI told bdnews24.com that Atiqur was shot near a mosque on the north gate of Ganabhaban around 11:45pm on Friday.
"It is suspected that he was hit by a bullet fired from his own gun," he added.