A sound resembling a thunderous explosion was heard around 8 p.m. on June 25 in the St. Helens area. Curious citizens flooded social media with questions about the origin of the boom that some said shook homes and rattled windows. According to St. Helens Police Chief Terry Moss, the first reports of the sound came in at 8:22 p.m. Moss said his department fielded 11 calls regarding the boom, mainly from residents on the west side of town. The cause of the sound has not been determined. Moss said this time of year is marked by frequent firework and "loud boom" reports. Without more definitive information, Moss said the matter would be considered closed.