A Spanish tourist has died after a suspected carbon monoxide leak in a west London hotel.
The Mayflower Hotel in Kensington was evacuated after emergency services were called at about 13:50 GMT on Monday.
One man was pronounced dead at the scene. Another Spanish man in his 30s, thought to have been staying in the same room, is in a critical condition in hospital.
Scotland Yard said initial carbon monoxide tests showed high readings.
Firefighters wearing breathing apparatus carried out a sweep of the hotel to check levels of the deadly gas, the London Fire Brigade said.
A spokesman added: "Crews isolated the gas supply and ventilated the building."
Police said initial tests found the readings were high, although the investigation run by police and the Royal Borough of Kensington and Chelsea's environmental health department has not yet concluded.
Some 29 people were evacuated from the hotel, which remains closed although the scene is now safe, police added.
A spokesman from Spain's Ministry of Foreign Affairs said its London consulate is helping the victims' families.
Scotland Yard said a post-mortem examination is yet to be held and the death is being treated as "unexplained".
The hotel did not respond to a request for comment.