BEIRUT – The United Nations gave a grim new count Wednesday of the human cost of Syria's civil war, saying the death toll has exceeded 60,000 in 21 months – far higher than recent estimates by anti-regime activists.

The day's events illustrated the escalating violence that has made recent months the deadliest of the conflict: As rebels pressed a strategy of attacking airports and pushing the fight closer to President Bashar Assad's stronghold in Damascus, the government responded with deadly airstrikes on restive areas around the capital.

A missile from a fighter jet hit a gas station in the suburb of Mleiha, killing or wounding dozens of people who were trapped in burning piles of debris, activists said.