It is understood three masked men, one armed with a gun, burst into a house in the Mayfield area, attacking one of the occupants.
Councillor John Blair said: “I am absolutely shocked and appalled at what has happened tonight.
“This incident took place during early evening on a busy street when many residents were going about their business. It is unacceptable that the perpetrators felt they could put the safety of many at risk by carrying out this horrible crime.
“The community is united in its condemnation of this incident and don’t want to see this type of crime on the streets of Glengormley. I am appealing for anyone with information to contact the PSNI has soon as possible so those behind this attack can be removed from the streets immediately.”