TISHOMINGO, Okla. (KFOR) – The National Transportation Safety Board released its findings from an investigation into a crash that caused the death of six teenage Tishomingo girls.

The teens died when the 2015 Chevrolet Spark they were traveling in was struck by a 1994 Peterbilt tractor-trailer at the intersection where Oklahoma 22 meets U.S. 377, at around 12:19 p.m. on Tuesday, March 22.

The tractor-trailer – operated by Burton Trucking LLC, an intrastate trucking company based in Burneyville, Okla. – was hauling gravel and heading south on U.S. 377, approaching the Oklahoma 22 intersection, according to NTSB officials.

U.S. 377’s posted speed limit was 50 miles per hour.

The Chevy Spark, driven by a 16-year-old, was heading east on Oklahoma 22, approaching U.S. 377.

Oklahoma 22 was controlled by a stop sign at the intersection.

The Chevy turned left in front of the tractor-trailer and was hit on its front-left side. It came to a stop on a gravel road approximately 364 feet from the point of impact. The tractor-trailer went off road and came to a stop approximately 241 feet from the point of impact, NTSB officials said.

“Postcrash toxicology reports indicated that the car driver was negative for alcohol and positive for cannabis, and the combination vehicle driver was negative for alcohol and other drugs,” NTSB officials said.

The driver of the Chevy was issued an intermediate driver’s license less than six months prior to the crash.

“According to the state of Oklahoma‘s Graduated Driver License requirements, a driver who is issued an intermediate license may carry only one non-household passenger in the vehicle unless accompanied by a licensed driver at least 21 years old,” NTSB officials said.

An Oklahoma Highway Patrol report released in March said that the Chevy did not yield to the stop sign at the intersection.

NTSB was assisted by the Oklahoma Department of Public Safety and the Oklahoma Department of Transportation.