The London Ambulance Service has tweeted that members of its hazardous area response team remain on standby at The Shard. They were reportedly called to the protest at 4.40am this morning.
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Coal's share of the power mix had fallen to 7%, while wind climbed to new highs to provide 15% of the country's electricity.
State Department spokeswoman Heather Nauert said Pence "was ready to take this opportunity."
Opposition activists said government forces have brought in more reinforcements in recent days.