April 20 (Reuters) - A Russian Sukhoi-34 supersonic warplane accidentally fired a weapon into the city of Belgorod near Ukraine late on Thursday, causing an explosion and injuring three people. Belgorod region governor Vyacheslav Gladkov announced a state of emergency overnight and said there was a crater measuring 20 metres (65 feet) across on one of the main streets. See here for a complete list of exchanges and delays