A man suffered a head injury in a hammer attack sparked by a row about queuing at a cashpoint.
A 16-year-old boy armed with a hammer attacked the 41-year-old in Gale Street, Dagenham, on Wednesday evening.
Detectives said a 17-year-old man then joined the attack leaving the Dagenham man with a head injury after 6.20pm.
Police have arrested a 16-year-old and a 17-year-old. They have both been bailed to December.
Anyone with information is urged to call CID Det Con Chris Hagan by calling 101 or Crimestoppers on 0800 555 111, quoting reference CR5119528/12.
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