Clashes have caused some casualties , a statement from the mayor 's office says . Authorities advise residents to stay in their homes as violence erupts . - The government has declared three days of national mourning for those killed and injured during protests on Friday. In response , Ukrainian air and ground forces attacked the airport .
Clashes have caused some casualties , a statement from the mayor 's office says . Authorities advise residents to stay in their homes as violence erupts . Pro-Russian separatists seized Donetsk airport terminal . In response , Ukrainian air and ground forces attacked the airport .