At least two people have died during anti-government protests that followed the funeral of a teenager who died nine months after being struck by police teargas. In Istanbul, a 22-year-old man was killed in a fight between groups on Wednesday while police were firing water cannons and tear gas to stop crowds from entering Istanbul's main square. In the city of Tunceli, a police officer died of a heart attack after fights with anti-government protesters. Officials denied reports that the scuffle was caused by tear-gas fired by police. The death and burial of 15-year-old Berkin Elvan has become a flashpoint in the increasingly turbulent public feud with Turkish Prime Minister Tayyip Erdogan.