The Met confirmed a 31-year-old woman and her two daughters, aged eight and three were taken to hospital with ‘potentially life changing injuries’ after the attack on Lessar Avenue, just yards away from Clapham Common.
Three other adults and police officers who were thought to have come to their aid were also taken to hospital.
Superintendent Gabriel Cameron confirmed this morning that the substance used in the attack was an alkaline.
Supt Cameron added: ‘Three women – two in their 30s and one in her 50s – who were injured when they bravely came to the aid of the family, have all been discharged from hospital with minor burns injuries.
‘A man in his 50s who also helped declined hospital treatment for minor injuries he suffered.
‘Five officers who were injured as they responded have all been treated and have left hospital.
‘All these members of the public, and my officers, deserve enormous recognition and praise for coming to the aid of this woman and children in what must have been a terrifying scenario. We will provide them with all the support we can.
‘I also want to commend nearby hotel staff after victims and officers sought refuge and water there following the incident.’
Officers are searching for a man seen fleeing the scene towards Clapham Common, assisted by a police helicopter.
The Metropolitan Police say they believe the man and woman knew each other and described the attack as ‘targeted’.
Latest London news
To get the latest news from the capital visit Metro.co.uk’s London news hub.
CCTV footage shows the suspect ramming his car into someone before throwing a child onto the ground.
A couple who live on the street say they ran outside after hearing a cry for help and a car crashing.
The man said: ‘We came outside and saw this guy and he took a girl out of the car and he slammed her to the ground twice.
‘I chased him half way down the road, but I was in slippers so didn’t get very far.
‘As I came back, that’s when I saw the woman who had been attacked, so I ran inside to get some water and just sprayed her down with water.’
Another witness who tried to wash the chemical off the woman’s face told Sky News: ‘It was horrific. First a man grabbed a kid – a girl aged two or three from a white car.
‘He threw her onto the floor – twice! It was the worst thing I’ve ever seen.
‘I then ran into my house, grabbed a water bottle and threw water on her eyes. Her lips were black. Her skin looked burnt.’
Get in touch with our news team by emailing us at firstname.lastname@example.org.
For more stories like this, check our news page.