Chechnya, a poor and predominantly Muslim region, has seen attacks targeting security officials and a rebellion since Moscow fought two wars with separatists there after the collapse of the Soviet Union in 1991.
Kadyrov said the attackers were two brothers from the neighboring Ingushetia region who were working in a bakery in Chechnya, adding that they were killed while trying to seize weapons.
And Russian news agencies had earlier quoted sources as saying that the two policemen were killed in an exchange of fire with the attackers.
In video footage posted on social media, two men were seen lying in the middle of a crowded street in Grozny, 1,490 kilometers from Moscow, while police diverted traffic.
Reuters could not immediately verify the photos.
In October, two police officers were killed in a shootout with militants in Grozny.