Vernon Miller thought he heard an explosion near his Pine Street home in Hopkinton at about 10:30 p.m., Monday, Jan. 15. Shortly thereafter, he heard sirens, stepped out his door and saw bright orange flames coming from the construction site of the Slusser Senior Center at Houston Fields. He grabbed his camera and by the time he retuned outside, the building was fully ablaze. The two-story 7,000-square-foot building was destroyed by fire in what fire officials confirmed was arson.