A 12-year-old boy was among those arrested after police came under attack on Thursday night.
A police chief said that he believes officers were “lured” into part of Derry in what was “orchestrated disorder.”
They were attacked with petrol bombs and three teenagers have been arrested.
Officers were initially called to a security alert in Moss Park near St Paul’s Primary School, which was being used as a polling station, at around 7pm.
PSNI Superintendent Gordon McCalmont said: “There is no doubt my officers were lured into the area this evening and that those involved in this orchestrated disorder had one aim in mind - to attack police.
“This was all the more reckless by the fact that one of the petrol bombs hurled at police landed in close proximity to young children who could have been left seriously injured, or worse.
“This security alert is the second this month in this area, impacting the same community that was disrupted on May 2 during local Council elections.
“It cannot be lost on anyone the disruption this has caused in the local community, let alone the potential for serious harm that could have been caused.
“I want to thank the public for their patience however when it comes to keeping people safe we take no chances. I would urge anyone who has information about the disorder this evening to contact police at Strand Road on 101 quoting reference number 1639 of 23/05/19.”
Two teenagers aged 17 and a 12-year-old boy have been arrested in connection with the disorder. All three remain in custody.
Six petrol bombs, 20 paint bombs and two crates of empty bottles were recovered by police.
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