Updated 1.05pm
A 16-year-old boy is in custody after two males on a moped carried out five acid attacks across London in less than 90 minutes, police said.
The teenager was arrested on suspicion of robbery and grievous bodily harm following the assaults, which the Metropolitan Police said appeared to be linked.
Two involved victims having their mopeds stolen, while one victim has been left with "life-changing" injuries after being doused on Thursday night in the east of the capital, the force added.
Labour MP Stephen Timms, who will lead an adjournment debate on acid attacks in the Commons on Monday, has called for tougher sentences for those found guilty, while Commissioner Cressida Dick revealed the Home Office is working with the Met to see if a change in the law is needed.
She branded acid attacks "completely barbaric", telling LBC: "The acid can cause horrendous injuries; the ones last night involved a series of robberies we believe are linked - I am glad to see we have arrested somebody."
The 16-year-old youth is being held at an east London police station.
London Ambulance Service said they were called to the first attack in Hackney Road at 10.16pm, while police were alerted to the night's final assault at 11.37pm.
At the start of the rampage, a 32-year-old moped rider was approached by the pair as he drove towards the Hackney Road junction with Queensbridge Road.
Two male suspects tossed a noxious substance into his face before one of them jumped on to the victim's vehicle and drove away.
One witness saw police pouring huge bottles of water over the victim just outside her flat.
Sub-editor Sarah Cobbold, 29, told the Press Association: "I had thought someone must have chucked petrol or acid on him or something because they were covering him in water, but I have never seen that reaction to an attack, I thought maybe there had been an accident."
Police said the man had been taken to an east London hospital and they were awaiting an update on his injuries.
Little more than 20 minutes later, at around 10.50pm, another victim had been sprayed with a searing liquid by the pair at the Upper Street junction with Highbury Corner in Islington.
The victim was taken to a hospital in north London.
Then at around 11.05pm, the fast-moving attackers swooped on a man in Shoreditch High Street, tossing a substance in his face.
His injuries were not life-threatening, police said.
Within 15 minutes, the attackers appeared to have struck again, launching a corrosive substance at a man in Upper Clapton Road, causing "life-changing" facial injuries.
The final assault was reported to police at 11.37pm, when another man was confronted as he sat on his moped in traffic in Chatsworth Road.
After again spraying a liquid in the victim's face, the moped was stolen and both attackers fled.
Hazardous area response units were sent by the ambulance service to four of the scenes, while the victim of the Chatsworth Road attack took himself to hospital.
The attacks come just days after John Tomlin, 25, appeared in court accused of throwing acid at aspiring model Resham Khan, 21 and her cousin Jameel Muhktar, 37.
They were left with life-changing injuries after the attack on Ms Khan's 21st birthday in Beckton, east London.