BANGKOK—A massive explosion at a chemical factory on the outskirts of Bangkok early Monday killed at least one person, injured dozens more, and damaged scores of homes, while prompting the evacuation of a wide area over fears of poisonous fumes and the possibility of additional denotations. Dense clouds of black smoke continued to billow from the site late in the day. Winds shifted and started blowing toward the city’s center, and evacuation centers were set up in a school and a government office for those forced from their homes. The fire broke out at around 3 a.m. at a foam and plastic pellet manufacturing factory just outside Bangkok near Suvarnabhumi Airport, with the explosion blowing out windows of surrounding homes and sending debris raining from the air. The blast could be heard for kilometers (miles) and surveillance video from a nearby house captured the bright flash and boom, followed by …