Ukraine government and separatists trade blame over attack on convoy, reportedly hit by artillery near Luhansk. Al Jazeera's Emma Hayward reports from Slovyansk. Subscribe to our channel http://bit.ly/AJSubscribe Follow us on Twitter https://twitter.com/AJEnglish Find us on Facebook https://www.facebook.com/aljazeera Check our website http://www.aljazeera.com/