6:00 AM PT 5/29 -- Law enforcement sources tell TMZ Ramona caused the pile-up. She took her eyes off the road for a second and did not see a vehicle stopping in traffic ahead of her. Singer's Maserati rear-ended the vehicle, causing a chain reaction into the other cars. Singer only suffered minor injuries. No one else was injured.
Law enforcement also tells us no alcohol or drugs were involved, and no arrests or traffic tickets were issued.
Ramona Singer had a rough start to her long Memorial Day Weekend after getting in a nasty fender bender, but she's on the mend now ... TMZ has learned.
"The Real Housewives of New York" star had left her home in Southampton, NY Saturday and was traveling along Montauk Highway in her Maserati when she rear-ended a Mazda ... according to sources close to Ramona.
We're told it was a 4-car pileup caused by a sudden stop by the first car, the Mazda was car #3 ... and Singer's Maserati was in the back.
Our sources say Ramona wasn't seriously injured, but was transported by ambulance to a nearby hospital with bruises and minor aches and pains. She was treated and released shortly afterward.
We're told she's still shaken up, but is doing okay and recovering nicely.
As for her car ... it was totaled due to significant front end damage, but don't worry -- it was insured.