Los Angeles Police Chief Michel Moore said at a news conference on Monday there was a “significant miscalculation” by the bomb squad that caused a fireworks explosion on June 30.
Moore said the bomb squad thought they were detonating 16 pounds of fireworks when they were detonating more than 42 pounds.
The increase in weight overloaded the device that was only meant for up to 25 pounds of explosives.
"We're committed to identifying how this occurred and ensuring it never happens again," Moore said.
There were 17 non-life-threatening injuries and zero deaths from the blast, but it did destroy or damage multiple buildings.
There were 13 businesses, 37 cars and 22 homes that were impacted by the blast.
Moore says he believes it was an accidental mistake but will hold accountable those who are responsible for it.
The police are also checking if the device was defective during the blast.
Protocols changed at the station as a result of the mistake and detonations now require a captain, two bomb technicians and a supervisor to sign off on them.
“While these investigations are not complete, based on the information gleaned by the interviews completed as well as in consultation with other bomb squad operations, here locally as well as across the country, we have taken significant steps to strengthen operating protocols, documentation, oversight of any destruction of fireworks or other explosive materials in the city,” Moore said.