The shooting of a man arrested during an anti-terror raid in east London was an "accident", the Independent Police Complaints Commission has said.
The brothers said they feared for their lives during the raid
The firearms officer involved committed "no criminal or disciplinary offence" when Mohammed Abdulkahar, 23, was shot at his home in Forest Gate, on 2 June.
The man's sister Humeya Kalam said the family felt "disgusted" by the report.
Meanwhile, Mr Abdulkahar has been arrested on suspicion of making pornographic pictures of children.
Police said he had been bailed to return to a London police station on a future date, pending further enquiries and consultation with the Crown Prosecution Service.
His solicitors said he "strenuously denies" the allegations.
Police were hunting for a suspected chemical device when they raided the Forest Gate house and shot Mr Abdulkahar in the shoulder.
He and his brother Abul Koyair were arrested but were later released without charge when no evidence of involvement in terror-related activities was found.
Police searched 46 and 48 Lansdown Road for a device
Police said computer and electrical equipment had been seized during a search of a house in London - understood to be the one raided in Forest Gate on 2 June - and passed to the Child Abuse Investigation Command for further examination.
Miss Kalam said the family thought the report had been rushed.
"I feel we've been let down by the IPCC as well as the police," she said.
Meanwhile, Mr Abdulkahar's lawyers released a statement saying they were "not satisfied" the inquiry had been thorough and would be challenging the findings.
Scotland Yard has released a statement saying it regrets that an "accidental discharge" caused injury in the raid on the house in Forest Gate.
In her report into the incident, IPCC Commissioner Deborah Glass said: "I am satisfied there is no evidence of intent or recklessness on the part of the firearms officer and that no offence was committed in the firing of the weapon.
"There is no evidence to support the speculative reporting that the weapon was fired by one of the brothers, or that it was a deliberate act by the police officer."
She concluded the gun, which had its safety catch off as the officer entered the house, had been fired by accident.
The investigation would not be referred to the Crown Prosecution Service (CPS) for consideration on criminal charges, Ms Glass said.
While the injury to Mr Abdulkahar was serious enough to merit a grievous bodily harm charge, there was no evidence of intent on the part of the police officer, she added.
Neither was there scope for prosecution under health and safety laws.
Met Assistant Commissioner Tarique Ghaffur said: "We welcome these findings but recognise the impact that this incident has had on the local community.
"I do not shy away from the fact that we have learnt important lessons regarding community consultation and engagement from these events."
The brothers, who had been held under the Terrorism Act 2000, were released on 10 June after police found no trace of an alleged chemical device at their home.