A 49-year-old woman from Idaho Falls was killed Sunday night after a two-vehicle crash sent both cars into a pond off U.S. Highway 20, according to the Madison County Sheriff’s Office.

The victim has been identified as Florrita Harker. Officials say she was found trapped in a vehicle submerged in water near mile marker 337, just outside Rexburg.

Emergency crews and bystanders worked to pull Harker from the car and attempted CPR. Despite their efforts, she was pronounced dead at the scene.

The crash involved a Chevrolet Impala and a Ford Explorer. All other occupants made it out safely.

“It’s unclear how the crash occurred,” the sheriff’s office said in a press release. “We are grateful to the citizens who stopped to assist and those who called 911 immediately after the crash occurred.”

Idaho State Police and Rexburg Police assisted on the scene and are continuing to investigate the incident.

According to a statement from the Rexburg Police Department’s official Facebook page, the crash shut down southbound lanes of U.S. 20 for several hours. As of 10 p.m. Sunday, all lanes had reopened.