Weekend rain caused major flooding in western Connecticut and turned deadly at the Little River in the town of Oxford, about 65km southwest of Hartford.
In two separate incidents, one woman was killed in her car and the other as she was attempting to cling to a sign, Oxford Fire Chief Scott Pelletier told a press conference on Monday.
In both cases, firefighters were on scene and attempting to rescue the women when floodwaters swept the victims away, Pelletier said.
Governor Ned Lamont, calling it a "historic storm," declared a state of emergency to help expedite state and federal recovery funds.
"It's just a reminder that we have to hang together at a time like this," Lamont said.
Commanding Officer Daniel Loughman of Connecticut state police announced the two deaths.
Media reports, citing police, identified the women as Ethelyn Joiner, 65, and Audrey Rostkowski, 71.
Their bodies were recovered on Monday after officials first responded to their distress on Sunday, Loughman said.
State police were able to rescue by boat an unspecified number of people stranded in two separate locations, Loughman said.
Search dogs and drones continued to comb the area on Monday, he said.