According to police, a car stopped outside Amrapali apartment in Sector 45 at around 1.45 AM and its occupants asked the guards to open the gate.
When the guards resisted, the occupants of the car shot at them and injuring two but fled after the third guard fired in retalition.
Guards Ashok Shahi and Anokhe Lal were injured in the firing while their colleague Anuj Thakur came to their rescue and fired at the criminals who then fled from the spot.
Supervisor Ashutosh Roy has lodged FIR against the unknown persons at Sector 39 police station.
The injured guards were admitted at the hospital and their condition was stated to be stable by late evening.