ALEPPO, Syria — Rebel shelling killed two Russian nurses and eight civilians Monday in Aleppo, and a Russian fighter jet crashed as it was returning to an aircraft carrier in the Mediterranean after a sortie over Syria, but the pilot ejected safely, Moscow officials said.

The shelling that targeted government-controlled western Aleppo was one of the most intense in recent days. It coincided with a crushing air and ground assault that has seen forces loyal to Syrian President Bashar Assad recapture more than half of opposition-held eastern Aleppo.

Russia and militias allied with Iran and Lebanon’s Hezbollah have been staunch supporters of Assad in his country’s bitter civil war, now in its sixth year.

The shelling initially killed one female nurse and wounded two Russian medics working in a field hospital, a Russian officer told reporters in the northern city. He spoke on condition of anonymity in line with regulations.

Another nurse who was wounded later died, the Russian Defense Ministry said.

At the U.N. Security Council, meanwhile, Russia and China blocked a draft resolution demanding a seven-day truce in Aleppo.