Torrential overnight rain triggered severe flash flooding across Boston’s South Shore on Thursday, dumping as much as seven inches of water on Weymouth and more than six inches on neighboring Hingham in roughly six hours. Boston 25 News characterised the event as a one-in-200-year rainfall for parts of the region, while the National Weather Service clocked downpours at up to two inches an hour and issued a “considerable” flash-flood warning for Boston and at least a dozen surrounding communities until 11:15 a.m. local time. Transportation ground to a halt during the morning commute. Massachusetts State Police shut both directions of Interstate 93 at multiple exits after floodwaters inundated the roadway, and MassDOT urged motorists to avoid the area. The MBTA suspended Red Line service between Quincy Adams and Braintree because of flooding at Braintree Station, and local police reported numerous vehicles stranded on submerged streets in Braintree, Weymouth and Hingham. Emergency crews rescued several motorists, including an Air Force veteran whose car stalled in waist-deep water in Braintree, but authorities reported no serious injuries. The weather service cautioned that although the heaviest rain had passed, many roads remained impassable and additional storms could redevelop along the East Coast later in the day. Massachusetts is the latest state hit by flooding this month, following deadly deluges in Texas, North Carolina and New Mexico. Officials urged residents to stay off flooded roadways, warning that as little as two feet of moving water can sweep vehicles away.