DAVIDSONVILLE, Md. (WJZ)—Four people were killed when a teen drove the wrong way down Route 50 in Davidsonville. Now there’s new insight into what caused that tragic crash.

Meghan McCorkell has the latest on the investigation.

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Toxicology reports show the teenaged driver who was going the wrong way was under the influence, and so was the driver she hit.

For 15 minutes, drivers frantically called 911 to report a car driving the wrong direction on Interstate 97 and Route 50.

“I don’t think they had a clue they’re on the wrong side of the road,” said one caller.

But police didn’t catch up to Brittany Walker, 19, before she crashed head-on into a BMW.

She died, along with 18-year-old passengers Breanna Franco and Zachary Rose. The other driver, 55-year-old Terry Davis, was also killed.

Now investigators say both drivers were under the influence.

“She was driving on the wrong side of the highway. And I don’t know if alcohol was related or not, I just don’t know,” said Brittany’s grandfather Norman Walker before the toxicology reports were released.

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Walker’s family struggles to figure out why the teen was on the wrong side of the road. The family of Terry Davis wants to know where were the police.

“Why weren’t the cops there to stop them before they hit Terry?” said Alice Davis, victim’s mother.  “Any car, any car that night. It could have been anybody they passed.”

Sam Wyatt was nearly caught up in the crash.

“Adrenaline takes over and I’m going into survival mode at this point,” Wyatt recalled.

He swerved just in time to avoid being hit by Walker’s car.

Wyatt was along I-97 North when the Chrysler flew by him going the wrong direction. It would go just five more miles before the crash.

“Either they’re looking to hit someone or they’re just that far out of control,” Wyatt said.

Now he’s relieved he wasn’t hit and his heart goes out to the families of those killed.

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WJZ has learned Brittany Walker was ticketed in 2010 for going 91 mph on a 65 mph road. Investigators say a small amount of marijuana was also found in Walker’s car.