Terrified football fans ran for cover after a flare was hurled into the Leazes by Manchester City supporters.
The flare hit a pensioner and narrowly missed a 10-year-old girl.
The canister swamped Newcastle supporters in thick blue smoke.
Newcastle fan Mark Steadman said the flare hit his brother Paul in the back.
Mark Steadman: "The lady behind me took the brunt of the attack after it bounced off my brother Paul’s back. It was quite scary at the time.
"It spoilt the game for the people sitting in the area. The poor lady was still wiping residue of her clothes at full time.
"I have a friend sitting in the other end of the ground who saw the smoke so I can safely say most of the ground must have seen it."
A spokesman for Northumbria Police said the incident was not being investigated.
It follows on from an incident at the Etihad Stadium when a flare was thrown during the Manchester derby.
A spokesman for Manchester City said the club had no comment to make about the incident in Newcastle.
Northumbria police say they won't be investigating the incident ... but ...
Police are investigating an allegation of racist abuse after Manchester City star Aleksandar Kolarov became involved in a heated exchange with a Toon fan at St James' Park.
Northumbria Police spokesman: "Northumbria Police has received a report of racist language having been used at the St James' Park stadium during the Newcastle United v Manchester City match.
"Northumbria Police takes such allegations extremely seriously and enquiries are ongoing into the incident."
It is understood 27-year-old Serbia international Kolarov became involved in a lengthy exchange with a supporter carrying an Albania flag as he warmed up on the sideline during the game.
There is a long history of tension between Serbia and Albania, particularly over the disputed Kosovo region.
Neither club was commenting on the matter, although it is understood that Kolarov will be spoken to by police next week.
The defender was introduced as a 37th-minute replacement for the injured Samir Nasri, but was also substituted 18 minutes from time.