The site of the crash near Tishomingo, south of Oklahoma City.
CNN  — 

The car driven by six high school-aged girls who died in a crash with a semitruck on Tuesday came to a “rolling stop” at a stop sign before entering the highway, witnesses said, according to an ongoing National Transportation Safety Board investigation, as the first victim was identified on Friday.

The girls were riding in a small passenger vehicle when it collided with a semitruck at an intersection in the city of Tishomingo, about 122 miles south of Oklahoma City.

On Friday, one of the victims was identified as 15-year-old Brooklyn Triplett. Brooklyn’s grandmother, Vada Triplett, confirmed her granddaughter’s death to CNN.

“Brooklyn was an amazing girl. She stood up for her beliefs and did not keep quiet when she felt someone was wronged.” Triplett told CNN. “She was so funny, witty and smart. Words can’t describe the wonderful light she had.”

There is a stop sign regulating traffic at the intersection where the crash occurred and the posted speed limit for the highway is 50 mph. Witnesses said the Chevy entered US-377 after making a “rolling stop” at the stop sign and was hit by the semitruck on the front-left, which pushed it off the roadway, according to the update.

The semitruck then veered off the road and came to stop in a private driveway off the highway. The driver of the truck was uninjured, the statement said.

The investigation is continuing and the NTSB, in coordination with the Oklahoma Highway Patrol, has sent a team of four investigators and a family assistance specialist to Oklahoma to look into several issues.

They will be evaluating highway conditions, like lighting and weather conditions, as well as accident histories at the site and potential reasons behind human error. They will also examine the vehicle’s compliance with federal and state regulations.

A memorial set up for the high school students who died Tuesday

Investigators will reconstruct the crash events and analyze physical evidence and vehicle damage, the statement said.

The team’s on-scene work is expected to conclude by Monday and a preliminary report is expected late next month. The full investigation – which would include probable cause and any contributing factors – will be completed in the next year or two.​​

​”On behalf of our students, staff, families, and community I want to thank you for your thoughtfulness, prayers and encouragement,” said Bobby Waitman, Tishomingo Public Schools superintendent, in a statement.

“As we begin the process of broken hearts, I am reminded that our greatest priority as educators is to meet the emotional, mental, social and physical needs of our students. This is our focus at this time - and every day that we serve our students,” Waitman’s statement added.

Rebekah Riess contributed to this report