Three people are in hospital after a chemical spill from a lorry near Buckingham Palace.
Emergency services were at the scene in central London with six people being assessed by paramedics.
London Fire Brigade said it was called just after 11am to reports of a spill outside the Grosvenor Thistle Hotel.
A London Ambulance Service spokeswoman said emergency services had closed off parts of Buckingham Palace Road.
She added: "So far three people have been taken to hospital. Staff are assessing six at the scene. Symptoms are sore throats and headaches - minor injuries."
Scotland Yard said the spill near the Palace involved materials which fell from the lorry.
A fire brigade spokesman said no evacuations took place at the hotel but a 25-metre cordon was put up.
"We believe it was brick acid that had fallen from the lorry and people had complained about being injured to their faces from breathing it in," he added.
"It fell from the lorry and was kicked up by passing traffic."