NAHANT – In 38 years as a police officer, Lt. Thomas Hutton said he has never done what he found himself doing Saturday evening.”I started running with my weapon drawn yelling to people, ‘Get down, get out of here,'” Hutton said Monday as he described how he responded to a police dispatch call about two men shooting at one another on Long Beach near the Ward Bathhouse.When Hutton stopped next to the bathhouse at 7:30 p.m., he said he saw at least 200 people on the beach. A man caught his attention, pointed to another man walking along the water line and said, “He just shot at me.”Hutton approached the man, who started running. Hutton, with his weapon drawn, gave chase.The man stumbled into the surf, grasping a bat in his left hand and a dark object in his right. Hutton took aim at him and ordered him to stop as the man dropped the object in his right hand into the surf. Hutton quickly apprehended him as police backup units headed down the beach.”I was extremely grateful when I heard the sirens. It was a great feeling when the cavalry showed up.”State and Lynn police converged on the bath house and took the man Hutton nabbed into custody. They charged Chrisna Choun, 18, of 42 Vine St., Lynn, with assault to murder, assault and battery with a dangerous weapon and a variety of firearms charges.He pleaded innocent to those charges in District Court Monday and is due in court today for a public dangerousness hearing after being ordered held without bail.Choun, according to court records, identified himself to State Police as a member of the Bloods street gang and said a member of the Crips, a Bloods rival gang, shot at him Saturday from a parked car while he was on the beach with friends.”Choun states that at this time he removes his .22 caliber pistol from his right front pocket and begins to return fire. Choun then realizes he is out of bullets because the gun slide is locked to the rear,” Trooper Raymond Thompson wrote in his police report.According to Thompson’s report, Choun ran down the beach chased by the man in the car, who police identified as Sophy Chhum, 19, of 85 Sheridan St. Choun managed to wrestle a baseball bat away from Chhum who pointed out Choun to Hutton.Chhum tried to leave the beach as police arrested Choun but bystanders pointed him out to officers and he was arrested on assault charges. He is scheduled to be arraigned today in District Court.According to Thompson’s report, Choun “stated he knew from word on the street that the Crips were looking to kill him due to a street level beef that he had with them.”Choun told police he lost his spleen and kidney a month ago after being shot by a Crip.