Police are searching for a man who suffered “serious injuries” to the right side of his face in connection with an alkaline attack in south London.
Abdul Shakoor Ezedi, 35, was last seen on Caledonian Road, north London, and police warned the public not to approach him.
Police said Mr Ezzedi had traveled to London from the Newcastle area.
A mother and daughter injured by a corrosive substance may have suffered “life-changing” injuries in the attack.
His 31-year-old girlfriend, 3-year-old daughter, and 8-year-old eldest daughter are also still hospitalized.
The suspect fled the scene in Clapham on Wednesday night.
He tried to flee by car, but crashed into a stopped car and fled.
Police believe the suspect is known to the family, but said the exact relationship is not yet clear.
Prime Minister Gabriel Cameron told reporters on Thursday that he had “no idea” of Ezzedi’s motives but was “completely confident” he would be arrested.
He said Mr Ezzedi was believed to be from the Newcastle area and the Hyundai car left at the scene belonged to him.
Supt Cameron added that he may have been known to police.
“While this appears to be a targeted attack, he is a dangerous individual and we need to find him as soon as possible,” the Metropolitan Police Department said in a statement early Thursday.
Prime Minister Supt Cameron said the suspect was last seen on Caledonian Road, north London, and anyone who saw him should not approach him and call 999.
There was an increased police presence on Caledonian Road on Thursday afternoon, including unmarked cars and police vans with blue sirens blaring.
A total of 12 people were injured in the attack. Of the four civilians who tried to help, three of them, two women in their 30s and one woman in her 50s, were taken to the hospital with injuries. Police said they “bravely came to the rescue of the family” and have now been released from hospital.
London Ambulance Service said it received reports of an incident near Clapham Common just before 19:30 GMT on Thursday and sent a response team, including three paramedics, to the scene.
A man in his 50s sustained minor injuries at the scene and refused treatment.
The five officers injured while responding to the attack were treated and released from hospital.
Metropolitan Police Commissioner Mark Rowley told the BBC on Thursday that some of the burns sustained by the mother and daughters in the attack were “quite severe”, but added that the full extent of their injuries was not yet known.
They were attacked on Lesser Avenue, near Clapham Common, at 7.25pm on Wednesday evening. Police were called to the scene after reports of an attack involving a suspected “corrosive substance”.
One witness told the BBC that the mother screamed “I can’t see, I can’t see” as she tried to help.
The couple, who live on Lesser Avenue, said they ran into the street after hearing cries for help and the sound of a car crash.
“When I went outside, there was a man. He took the girl out of the car and slammed her to the ground twice,” said the man, who did not want to give his name.
Witnesses said they saw the woman attacked after unsuccessfully trying to chase the man, and “went inside to get water and just sprayed her with water.”
He explained that her face had severe burns.
The witness’ partner suffered minor burns after tending to one of the children involved and was taken to hospital, but was later released.
Police appealed to members of the public who witnessed what happened to call 101, quoting reference CAD 7790/31 January. They also asked local residents and motorists to check their doorbells and dash cams for any footage that may show a man fleeing the area.
Police say the crime scene has now been set up and is likely to remain there for some time.