Panaji, May 22 : Three armed robbers during the wee hours of Monday opened fire at police on patrolling duty in South Goa, while they were trying to escape from the scene, police said. Verna Police Inspector Diago Gracias told IANS that the robbers fired two shots when they saw police were approaching to nab them. "This incident happened when they were trying to break the house. There were three robbers, who fired two shots and then escaped from the site," Diago Gracias said. He said that the incident happened near MES college at Zuarinagar in South Goa. "We are looking out for these robbers, investigation is on," he said, adding that one home guard sustained minor injury during the incident. "It is not known whether he was hit by a bullet. He was taken to the medical college for treatment and he is well," sources told IANS. Further investigating is on. /IANS