Ceuta: What triggered mass migrant crossing?

The massive influx of people was equivalent to around 70% of Ceuta's resident population. As the first reports of migrants reaching the Spanish enclave spread, more people headed north in the hope of reaching EU territory. It remains unclear what triggered the influx, but social media was awash with posts encouraging people to enter Ceuta in the days before the chaos began. Clémence Waller has more.