The driver, a 75-year old woman, and three people inside the building were transported to Stony Brook University Hospital.
The others hurt were a female employee, a mother and her 9-year old son.
There are a number of offices in the building, including a doctor's office and a law office.
The first 911 caller said a doctor and two other people were in the room that the car crashed into.
The building did not collapse but electricity was shut and the building was evacuated. The investigation is continuining.