Six teenagers were killed and two other people were injured when the SUV they were in struck a guardrail, turned over, and crashed into a pond, officials say.

The single-vehicle accident took place near Warren, Ohio, on Sunday morning, Lt. Ann Ralston of the Ohio Department of Public Safety said.

The teens, ages 14 to 19, were traveling in a Honda Passport at about 7 a.m., Ralston said.

An investigation is under way into what caused the crash.

Police are notifying next of kin, Ralston said.

Dive teams were called in to help rescue the injured, CNN affiliate WKBN reported.

Authorities found that the vehicle appeared to be overloaded, and that no one was wearing a seat belt, WKBN said.