It was not immediately clear what sparked the exchange that led to the shooting in the upscale Jadriyah neighbourhood, but the Kurdish peshmerga captain fled the scene shortly after Mohammed Bidaiwi, editor-in-chief of Radio Free Iraq, was killed.
"The peshmerga captain killed him after he stopped him (Bidaiwi) from getting into the compound," said a journalist at Radio Free Iraq who declined to be identified.
"We did not move the corpse yet... The officer responsible has disappeared."
"Our forces are laying siege to the presidential offices," said Ali Mussawi, who suggested the presidential guard was harbouring the officer.
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"If this brigade refuses to hand over the criminal, we have orders to break in and arrest him by force."
Radio Free Iraq is a branch of Radio Free Europe/Radio Liberty and Bidaiwi has been its chief editor since 2006.
The so-called "Talabani Compound" is just outside the heavily-fortified Green Zone, home to the prime minister's residence, parliament and the American and British embassies.