Four suspected gunmen behind the deadliest attack in Russia in 20 years are Tajik citizens
Police said on Twitter they were still searching for the assailant and posted a picture of a suspect without giving a name. There was no word on possible motivation for the attack.
The shooting took place at the University Hospital in Ostrava soon after 7am, Interior Minister Jan Hamacek told Reuters.
Prime Minister Andrej Babis told Czech Television the shootings occurred at close range in the waiting room, while Health Minister Adam Vojtech said six people had died.
Hamacek and Babis were headed to Ostrava, 350 km (217 mi) east of the capital Prague.