According to the Pune (Rural) Control, the SRPF jawan, identified as Sanjay Shinde, opened fire with his service revolver in Borawke Nagar and Morinagar Chowk areas.
He first fired at public in Morinagar, killing two persons and barely 15 minutes later, he opened fire in Borawke Nagar nearby where he felled one.
Later this evening, based on his mobile phone location, he was caught and arrested from adjoining Ahmednagar district where he had fled shortly after the incident.
A police team rushed to the firing spots, while others sealed off all exits from Pune, and scanned CCTVs, railway stations, bus depots and other places to trace him, said Deputy Superintendent of Police Ganesh More.
The deceased were identified as Anil Jadhav, Gopal Shinde and Prashant Pawar. There were no other casualties as panicked people ran helter-skelter to escape the bullets.
The motive behind his action, tentatively believed to be some financial disputes, is being probed, police said.
Police have seized Shinde's service revolver, his motorcycle, mobile phones and other things after the arrest, said a senior police officer.
In a precautionary move, police have deployed additional forces outside the trooper's home as a wave of anger swept among the people of Daund.