A World War II era bomb went off early Friday in the eastern Czech city of Ostrava during excavation work, killing a man and injuring another, police and media reports said.

"We can confirm the explosion was caused by World War II ammunition," police said on Twitter.

Local media said a 49-year-old man died while another man suffered a light head injury.

Police evacuated about 50 people from houses within 300 metres from the site.

World War II ammunition is often found in the northeastern Czech Republic through which the Red Army advanced in the spring of 1945.

Last autumn, police evacuated over 1,000 people on two occasions when unexploded ammunition had been found in Ostrava.