NEW YORK (WABC) -- Four police vehicles were involved in an accident Sunday on the FDR Drive in East Harlem.The officers, assigned to the department's elite new "SRG" tactical unit, had been travelling in convoy southbound at East 116th Street, when a car ahead of them slowed down.The first police car rear-ended that civilian, causing a chain-reaction that also included one other civilian car, which rear ended a third police vehicle.At least three officers were placed on backboards and hospitalized; cops say they, and at least one other driver, suffered only minor injuries.7 officers and 1 civilian were taken to NY Presbyterian Cornell with minor injuries. A second civilian refused medical attention.The highway was shut down while the officers were freed from their cars.The newly formed Strategic Response Group responds to major incidents and terror attacks.