Police were deployed in and around the Belgian city of Liege on Saturday to clamp down on a armed feud between rival groups of Chechens and Kurds after an assault the day before left one dead.

A Chechen man was killed Friday after being attacked by 20 to 30 men in Liege, Belgium's fifth-biggest city, a magistrate in the prosecutors' office told AFP.

The attackers -- all believed to be Kurds -- were black-clad and wore ski masks, some wielding baseball bats and at least one firearm.

An onlooker's video broadcast by RTL Info television showed the assailants running after a black sedan which crashed into a parked car. Four gunshots can be heard as the masked group crowded around the stopped vehicle.

That scene followed a brawl between a Chechen and Kurd in a service station on Thursday during which the establishment's owner and a customer were hurt trying to break it up, said the magistrate, Damien Leboutte.

Three Kurds identified from the service station's security cameras have been arrested for questioning.

Another 28 people -- all Chechens -- have been arrested for questioning and identity checks in relation to Friday's deadly assault, and at least one firearm, a Kalashnikov assault rifle, has been seized, the magistrate said.

"We've never seen such incidents before in Liege," he told AFP.

The nationalities and residency status of the suspects were being verified along with their identities, he said.

There were fears the feud could continue into the weekend, he said, with social media posts talking of the Chechen community seeking "vengeance" against the Kurdish community in the town of Verviers, east of Liege.

Police have been deployed to "secure" the area, the magistrate said.