They're looking at the possibility a beige van or large SUV with a box-shaped rear was involved and would likely have a black paint transfer or scrape mark on the front, left bumper.
Residents who live in the area say Green Level to Durham Road/Cary Glen Blvd intersection is dangerous and needs a traffic signal.
They point to a second serious accident that happened the day after Monday's fatal crash.
"We're afraid for our own children that this might happen again, especially in light of the fact that we have several people in the hospital now, four people in the hospital fighting for their lives," resident Dawn Cross told Eyewitness News.
Cary traffic engineers have looked at the issue in the past and concluded a light wasn't necessary. But now after the accidents, they're taking a second look at the issue. They say the road dips just before the intersection - which may impact driver's ability to see oncoming cars - and they're looking at foliage along the road.
"I'm not certain the trees impact that, but the hill we're looking at that. Whether a traffic light would be a good solution or something else, we're investigating," offered Cary traffic engineer Tim Bailey.
Bailey said the city may explore some short-term fixes.
"We're looking at temporary solutions such as blocking the median, putting a median barrier across the intersection, and just forcing people to u-turns until something more permanent can be established," said Bailey.
Cary city leaders say the issue is a top priority.
"As our community mourns the loss of a wonderful young lady, citizens can be assured that the Town of Cary is continuing to do what it takes to ensure that our intersections function appropriately and safely according to national standards," said Mayor Harold Weinbrecht.
Anyone who witnessed Monday's crash and can provide more information for investigators is asked to contact the Cary Police Department at (919) 469-4012.