A gunman killed six people on Tuesday at a hospital waiting room in the eastern Czech city of Ostrava before fleeing and fatally shooting himself in the head, police said.

It was unclear what motivated the Czech Republic's worst attack since 2015 when a man shot eight people dead and then killed himself at a restaurant in the city of Uhersky Brod.

"We have captured the shooting assailant. The 42-year old man had shot himself in the head before police took action, he is dead," police said on Twitter.

Police received calls about a shooting at 7:19 a.m. (0619 GMT) at the University Hospital in Ostrava, 350 km (217 miles) east of the capital Prague and near the border with Poland.

Officers were on the scene five minutes later.

Hospital director Jiri Havrlant told a televised briefing five people died in the attack and one died in surgery. Another two were seriously injured but no medics were hurt, he said.

The attack happened in the waiting room of the outpatient clinic and victims had been shot at close range, he said. They were all adults: four men and two women.

There was no word on possible motivation for the attack.