Ukrainian authorities said Thursday that a commercial ship arriving to collect grain hit a Russian naval mine in the Black Sea, injuring two sailors.The unnamed Panama-flagged ship was heading towards Ukraine's Danube ports when it hit a mine, causing it to lose speed and control and sparking a fire on the upper deck, Ukraine's border guards said.Ukraine has created a maritime corridor for commercial ships which first pass close to the shores of Bulgaria and Romania.The border force did not specify exactly when or where the incident happened.The Maritime Bulletin, a website that tracks the shipping sector, wrote that a Greek-owned, Panama-flagged ship called Vyssos had a mine explode under its stern on Wednesday morning while on its way to the port of Izmail.Previously two civilian cargo ships have been damaged by Russian mines, the Odesa Maritime Guard told AFP this month.In the incident reported on Thursday, the captain intentionally ran the ship aground to stop it sinking and Ukraine has sent out tugs that will take it into port.The Maritime Guard brought doctors who treated one of the injured sailors on the spot while the other was hospitalized and is in good condition.Ukraine has pushed back Russian warships in the western part of the Black Sea to allow some cargo ships in and out along a maritime corridor.But the water remains heavily mined, including by Russian planes, and is particularly dangerous in stormy weather.