Police said the injured, identified as Sonu, had been referred to a hospital in Delhi in view of his critical condition.
According to police, a gang of four suspected robbers struck at a jhuggi cluster on an under-construction apartment complex in Noida's Sector 122 around 2 last night.
But hearing noise, the workers woke up and raised alarm. Security supervisor Davinder, guard Ashutosh and gunman Mahinder rushed to the spot and challenged the robbers.
Police claimed the criminals opened fire at the security guards, who retaliated, injuring one of the robbers.