BOYERTOWN, Pa. -- A series of storms socked the Northeast with heavy rains and strong winds, causing the deaths of an 8-year-old boy and his pregnant mother whose car was swept away by floodwaters while she was on the phone with emergency officials.

The rain started falling Thursday night and continued through early Friday in most areas. The storms quickly intensified, causing minor to major flash flooding in several states and possibly spawning a tornado in a southern New Jersey town.

Authorities say a car driven by a pregnant woman in Pennsylvania was swept down the Manatawny Creek for about a half-mile on Thursday night. The woman's phone call then dropped, and emergency workers found the car in a tributary nearly five hours later.

The names of the woman and child have not been released.

Floodwaters also closed several streets in the Pittsburgh area on Thursday night, but most had reopened by morning. The storms also knocked down trees and power lines, causing sporadic power outages across the region.

Portions of southeastern Massachusetts were hammered by heavy rain overnight, with the National Weather Service reporting that more than 5 inches fell over a six-hour period in Plymouth. Some road closures were reported, but no injuries. A flood warning was in effect for Provincetown, at the tip of Cape Cod, until midmorning Friday.

In New Jersey, National Weather Service investigators were planning to examine whether a tornado touched down in Mount Laurel Township on Thursday evening. Trees were toppled and radar indicated the possibility of a tornado.

Parts of New Jersey received more than 3 inches of rain from the storm.