A man in his early 20s remained in critical condition Tuesday and on a life support system at a San Diego hospital after he was stunned three times by police with a Taser gun early Monday morning, San Diego police said. Officers were called to the L Street home after a resident reported a prowler and found a man, identified as Mario Gastelum, hiding underneath the house. Police fired the Taser gun twice to force Gastelum from the crawl space. He was shot a third time after he behaved violently en route to Physicians & Surgeons Hospital, police said. The Taser gun shoots a dart that emits 50,000 volts of electricity. Police said Gastelum was believed to be under the influence, possibly of PCP, and was resisting arrest.