With rain coming down so fast, storm drains couldn't handle the deluge of water. On Interstate 93 in Quincy, all were lanes closed at one point because of extreme flooding during rush hour. At least five cars were stuck on the highway until the water receded.

A "considerable" flash flood warning was issued in Boston on Thursday morning as heavy rain pounded the city and areas to the south. Four to 6 inches of rain fell in the towns of Canton, Quincy and North Scituate.