Islamic State militants are advancing on the Syrian town of Kobane, where they are battling Kurdish fighters.
The clashes are visible from Turkey, where some protesters have stormed a border fence to go to defend the town.
Earlier, the US said it had destroyed four tanks and damaged another during a fourth night of bombardments in Syria.
The UK parliament has voted to conduct air strikes against IS in Iraq, while Belgium and Denmark have also announced they will take part in the operation.