The rainfall was much more than your everyday summer storm, as residents in Connecticut and parts of New York were trapped in cars, restaurants and homes, forcing multiple rescue attempts by first-responders.

Watch the vid ... local firefighters in Oxford, Connecticut executed a daring rescue, pulling patrons trapped inside a restaurant to safety after gushing water flooded the building.

Firefighters guided the locals over a metal bridge to higher ground nearby. Debris -- including a rogue metal dumpster -- whizzed by at high speeds in surrounding floodwaters.

According to Connecticut Gov. Ned Lamont, more than 100 people were evacuated Sunday evening by search-and-rescue teams in the intense weather ... which continued into Monday morning.

Lives have already been lost due to the rainfall ... the bodies of 2 women -- both residents of Oxford -- were recovered on Monday.

Per Fire Chief Scott Pelletier, the first victim died when she was swept away in a flooded river, despite firefighters' attempts to reach her.

The second victim had reportedly climbed out of her vehicle to hold onto a nearby sign ... but she was also taken by the raging water.

Hurricane Ernesto was brewing over the Atlantic Ocean Sunday evening -- but that storm did not play a factor in the downpour that hit the East Coast. Professor of meteorology William Syrett compared the Connecticut-area storm to an oncoming train, telling AP News, "perfect conditions" for severe thunderstorms created excessive rainfall and flash floods.