BEIRUT (AP) — A suicide bomber blew himself up at the gates of a Syrian prison Thursday and rebels stormed in behind him, freeing hundreds of inmates as part of an offensive aimed at capturing key government symbols around the northern city of Aleppo, activists said.

Government forces, meanwhile, dropped crude “barrel bombs” in deadly airstrikes as both sides escalated their fight for the strategic city ahead of a second round of peace talks set for next week. Opposition leaders threatened to suspend the talks over the barrel bombings.