A flash flood warning is in effect until 9 a.m. for Boston and several communities south of the city, including Brockton, Quincy, and Randolph, officials said Thursday morning. The National Weather Service also issued a flood watch that will remain in effect until 4 p.m. for Rhode Island and eastern portions of Massachusetts and Connecticut.

The agency predicted rain would fall at a rate of 1 to 2 inches per hour, potentially overwhelming small creeks and streams, streets, highways and underpasses, as well as other poor drainage and low-lying areas.

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.