The teenager and a 54-year-old man were arrested on today (August 24) on suspicion of arson with intent to danger life and remain in police custody.
Officers were called to Indian Aroma restaurant on Woodford Avenue in Gants Hill around 9pm on Friday (August 22).
Of the five injured, two – a man and a woman – remain in a life-threatening condition.
Officers are also seeking two other victims they think left the scene before they arrived.
Detective Chief Inspector Mark Rogers, of the Met’s Central Specialist Crime North unit said: “While we have made two arrests, our investigation continues at pace so we can piece together what happened on Friday evening.
“I know the community are concerned and shocked by this incident.
“I would urge anyone with any information or concerns to come forward and speak to police.”
Anyone with information is urged to contact the Met via 101, quoting 7559/22AUG. If you wish to remain anonymous, please speak with Crimestoppers on 0800 555 111.
