The city center of Odessa is bracing for a potential attack by the Russian army on Ukraine's biggest port city. The mayor of Odessa says the situation is "tense", four days after the Russian army carried out its first strike at the city, in a residential area. There has so far been no victims from the strikes. "We are doing everything we can to make it safe to stay in the city," Gennadiy Trukhanov tells AFP. IMAGES AND SOUNDBITES