A flare was thrown into the disabled supporters’ section at Sunderland’s Stadium of Light during their match with Birmingham City on Saturday.
Police are investigating who threw the object from the stand above, which had been occupied by visiting fans.
Footage recorded by a fan shows what appears to be a flare land with a plume of blue smoke rising into the air.
It landed between the wheels of a wheelchair but no-one was injured, Northumbria Police said.
A spokesman said officers were trying to identify those responsible and the force asked anyone with information to get in touch.
Sunderland AFC condemned what it branded the “unacceptable conduct” of a “small minority of away supporters”.
“A pyrotechnic device was discharged in the North Stand Upper after Birmingham City opened the scoring in the 29th minute and it was subsequently thrown into the North Stand Lower,” the said in a statement.
“The individual responsible for this abhorrent act has been identified by CCTV and all relevant information has now been handed over to West Midlands Police, with club representatives continuing to directly support those impacted.”
It said that taking a pyrotechnic device into a football stadium is a criminal offence.
Meanwhile, more than 1,500 people have signed an online petition launched by Sunderland fans calling for the club to move the section for away supporters.
They warn that missiles thrown from the top stand are “now a regular occurrence” at home games.
The change.org petition says the club have tried to tackle the problem with stricter searches but it has proved “almost impossible to police”.
Sunderland coach Tony Mowbray said objects such as flares were “dangerous”, adding: “The authorities at each club, or the football authorities who govern the game, it’s something for them to address with police I assume.”