A 13-year-old boy received treatment to his eyes and a woman sustained a leg injury when pyrotechnics were set off at a football game.
Smoke bombs, bangers and flares were used in the section occupied by away fans during the game between Livingston and Rangers on Wednesday evening.
A police officer was struck by a coin thrown from the same area of Livingston's Tony Macaroni Arena during the Betfred League Cup quarter final.
Police have appealed for information.
The boy and the 26-year-old woman were treated by medics at the stadium and did not need to go to hospital.
Football banning orders
Ch Insp Neil Mitchell warned that it was only a "matter of time" before someone was more seriously injured.
"It is only down to luck that their injuries were minor," he added.
"One of my officers was also struck by a coin thrown from the same group of supporters. This is also unacceptable and will not be tolerated.
"We have a retrospective investigation ongoing and are working closely with both clubs to identify those responsible. I can confirm that we are following a positive line of inquiry."
He added: "We will deal with all those responsible in a robust manner including seeking football banning orders through the courts."