Flash floods hit several cities and towns south of Boston Thursday morning as historic rain brought traffic to a crawl and clogged streets and highways during rush hour.With rain coming down so fast,

I-93 was essentially a river Thursday morning as torrential downpours dumped up to six inches of rain across eastern Massachusetts. As you probably heard from your phone's alert system screaming at you,

Boston, Quincy, Brockton, and other South Shore communities are under a flood watch until 9 a.m., according to the National Weather Service.