The nature of the injuries from a fire that broke out on a London Duck Tours boat "could have been a lot worse", according to a police source.
Scotland Yard said police were called to the vessel just before midday.
A number of people were reported to be in the water at the time. Several Metropolitan Police units attended including the Marine Policing Unit and the police helicopter.
A number of people were recovered from the water. All 28 passengers and two crew members have been accounted for. The emergency services are in attendance at the scene.
Around 30 passengers have been rescued after a fire broke out on a tour boat on the River Thames shortly before midday.
Passengers were hauled to safety onto passing tour barges as flames ripped through the vessel on a stretch of water close to Lambeth Bridge in central London.
London Fire Brigade said a third of the boat was damaged by the blaze but everyone on board had been accounted for.
Carl Mills, 28, has been found guilty at Newport Crown Court of the murders of Kim Buckley, 46, her daughter Kayleigh, 17, and granddaughter Kimberley, six months, who all died when a fire he started ripped through their home in Cwmbran in September last year.
Firefighters in London have dealt with twice as many grass fires compared with last year as the heatwave across the UK continues.
There have been 1,010 incidents so far this summer compared with 535 from May 1 to July 15 last year and more are feared, the London Fire Brigade said.
Dave Brown, London Fire Brigade's head of operations, said: "A small spark from a cigarette is often all it takes to start a grass fire in these dry conditions. It really is important that smokers dispose of their cigarettes properly.
"Drivers also need to take care not to throw cigarettes out of car windows as they can easily burn grass verges.
"If you see a grass fire, don't attempt to put it out yourself as grass fires can be fast-moving and change direction without warning. Call the fire brigade and let us know where the fire is."
More than 60 firefighters are tackling a blaze at a city centre shop with 12 crews fighting a fire which broke out in Oldham Street, Manchester, at 2.50pm.
Area manager Warren Pickstone said: "Crews are doing their best to fight the fire. They've faced difficult conditions because the fire started in the storeroom of a shop so there's a lot of material burning in there.
"They're working to stop the fire from spreading to other buildings and we're working with GMP (Greater Manchester Police), NWAS (North West Ambulance Service) and other partners to take care of the community and limit the disruption.
"Unfortunately two members of staff were taken to hospital - one with burns, who had tried to fight the fire, and another was suffering from smoke inhalation."
West Midlands Fire Service has released CCTV footage of the moment it believes a Chinese lantern floated into a recyling centre in Smethwick, starting a huge blaze. In the short clip, the object appears after 11 seconds from the right of the picture.
Calls by the Liberal Democrat president Tim Farron for a ban on Chinese lanterns have been played down by Downing Street, in the wake of the Smethwick fire.
"The actual number of fires caused by Chinese lanterns is very small," a No 10 spokesman said.
"It is important that we always ensure that there is a proportionate response to any event and we always look at safety matters and make sure they are kept at the top of our concerns."
The West Midlands Ambulance team has treated a total of 13 people, including 12 firefighters, at the scene of the recycling plant fire in Smethwick.
In total three people were taken to hospital after more than 50,000 tonnes of recycling material was set alight.
Briefings are expected to take place today on road closures surrounding the factory.
Liberal Democrat president Tim Farron has repeated calls for a ban on Chinese lanterns following the Smethwick fire.
The Cumbrian MP made calls for the lanterns to be banned in 2012, saying "these lanterns are a spectacular sight to enjoy but many don't realise the harm they can do".
I hope that Defra agree that after the Smethwick fire last night an urgent review of the into the use of sky lanterns is needed.
As we now have daylight, firefighting can be more assertive extinguishing remaining 10% of recycling material still alight #SmethwickFire