Dangerous flash floods stranded motorists and left roadways under water. Some outdoor activities were canceled as communities scurried to keep pace with the rising waters.

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.

Portions of Interstate 93, a 190-mile-long highway that connects Massachusetts, New Hampshire and Vermont, were closed because of flooding, the Massachusetts State Police said. Several vehicles were stranded on the highway because of floodwaters, local news media reported.

Communities south of Boston have seen as much as 4 and a half inches of rain, with a flash flood warning still in effect.

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,