CrowdVoice, a user-powered service that tracks voices of protest from around the world, lists a timeline of Israeli air attacks on Gaza in 2014. Here's an excerpt from their “explore the backstory” section:

A series of abductions and murders has inflamed age-old tensions and sparked armed unrest in Gaza. It began on May 15, 2014, when two Palestinian youths were shot dead during clashes with Israeli security forces during a demonstration in the West Bank. Outrage grew when video footage of the killings emerged, showing that the unarmed teens were shot with live ammunition, despite Israeli assertions that only non-lethal munitions were used against protesters. Later, on June 12, three Israeli teenagers were kidnapped as they hitchhiked home from the West Bank. An Israeli military operation was launched to find the missing teens, and on June 30, their bodies were recovered. The government of Israel has blamed Hamas for the murders, and vowed swift retaliation. Hamas praised the kidnapping, but did not claim responsibility. In an apparent act of retribution, Mohammed Abu Khdeir, aged 16, was abducted near his home on his way to morning prayers and burned alive. Israeli authorities have arrested six people in connection with the teen's death. Tensions from the murders have boiled over into indiscriminate Palestinian rocket attacks into Israeli territory, and relentless aerial bombardment of Gaza.