BEIRUT (AP) — Syrian activists and rescuers say government warplanes and artillery have pounded the last rebel stronghold in the country, killing at least 14 people by midday.

Wednesday's attacks mark a month since government forces escalated their offensive on the rebel stronghold in northwestern Syria, home to 3 million people. The U.N. has warned its humanitarian operations in the region are at risk.

Rescuers say they struggled to respond to the intense bombing that began before dawn. Civil defense volunteers, known as White Helmets, said at least 15 were killed in Baraa, Serja and Habeet villages in southern Idlib.

The Syrian Observatory for Human Rights and activist-operated Baladi News agency reported 14 killed.

Syrian state media said one woman was killed in government-held northern Hama province after rebel shelling of the area.