TAMPA — They came from Massachusetts two weeks ago for a change of pace, spending their first few days as Floridians fishing, swimming, basking in the sun.But within a week, Jeremy Himmelman and Andrew Oneschuk knew something was off with their roommate, Devon Arthurs, who invited them to live in his apartment at the Hamptons at Tampa Palms subdivision, said Himmelman's sister Lyssa Himmelman.Himmelman, 22, and Oneschuk, 18, planned to leave today, but Tampa police say Arthurs, 18, shot both roommates Friday before briefly holding two customers and an employee hostage at a nearby smoke shop. There, police say, Arthurs boasted that he "blasted their head," before surrendering to officers and leading them to his apartment, where the young men appeared to have died from gunshot wounds.Arthurs, of 15350 Amberly Drive, is being held without bail at the Hillsborough County jail. He faces two counts of first-degree murder, two counts of aggravated assault and three counts of armed kidnapping.Lyssa Himmelman said her brother and Oneschuk had been friends for about a year. Jeremy, she said, had aspirations of enlisting in the military and Oneschuk planned to join the Navy. She said both men loved politics and history and could speak on the subjects for hours.She said her brother loved animals, hiking and spending time with his friends and girlfriend. She described Oneschuk as "a wonderful guy with a good heart."Lyssa Himmelman said she did not know Arthurs well, but heard he had extreme views, which caused conflict in the Tampa household. She described Arthurs as unsettling, dark and eerie.After the shootings, police say Arthurs entered the Green Planet Smoke Shop around 5:30 p.m. Friday, waved a gun and kept those inside from leaving the store.The store's manager, Fadi Soufan, who was not present for the incident but recounted to reporters what his employee had seen, said Arthurs ranted "the world was corrupt, crazy stuff like that, that he just shot someone at Hampton over there."Soufan added, "He wanted publicity. Actually, he pointed at the camera. He said he wanted CNN to come."The ordeal lasted about three minutes, Soufan said, and at one point Arthurs became angry and swiped some things off a shelf. He told people in the store that he was not going to kill them and that they were going to make it home.Soufan said no one in the shop recognized the man.Arthurs led police to his apartment, but authorities had concerns about explosives. The Tampa police bomb squad and Tampa Fire Rescue's hazardous materials team worked late into the night after the bodies were found searching Arthurs' apartment before detectives could begin their investigation of the home. Tampa police spokesman Steve Hegarty said Saturday he didn't know if bomb squad and hazmat personnel found anything suspicious.Lyssa Himmelman said loved ones from Walpole, Mass., are grieving for her brother and Oneschuk.Researcher John Martin contributed to this report. Contact Colleen Wright at [email protected] or (727) 893-8643. Follow @Colleen_Wright.