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.

Heavy rainfall caused areas of flooding on I-93 and other major roadways in Massachusetts on Thursday morning.

BRAINTREE, Mass. — Drenching downpours quickly turned highways and streets in eastern Massachusetts into rivers, just as traffic started to build for the Thursday morning commute. A large part of Interstate 93 in the Milton-Quincy area was underwater before 7 a.m. as torrential rain moved through.

The National Weather Service issued a flash flood warning for Boston, Quincy, Brockton, and other nearby communities. See where

Catastrophic floods can be difficult to prepare for. Sometimes evacuation is the right call, but if it’s too late the best bet is to find higher ground nearby. The stakes can be high, because a flash flood may give those in its path only minutes or seconds to react.