Father Jacques Hamel (84) was killed and four others were taken hostage in Saint-Etienne-du-Rouvray, a suburb of Rouen.
One of the hostages was critically injured and Islamic State have claimed responsibility for the attack.
In a letter to Normandy president Hervé Morin on behalf of the Channel Islands, External Relations Minister Sir Philip Bailhache and his Guernsey counterpart, Jonathan Le Tocq, expressed their sympathy, meanwhile, Chief Minister Ian Gorst tweeted his shock over the attack, which took place at about 9 am on Tuesday.
