In a news conference on Friday morning, Chief Investigator Pete Kotowski said the NTSB was looking at environmental factors, saying those factors - including nearby trees and the angle of the intersection - may have contributed to this crash.
They also said the bus driver, John Tieman, 66, from Beverly, New Jersey, had only been a bus driver for three weeks and had only been on the route for nine days.
Furthermore, Kotowski said the dump truck involved, driven by Michael Caporale, 38, from New Egypt, New Jersey, was carrying a load of asphalt and was slightly over the weight limit.
However, Kotowski did not offer any conclusions about the crash, saying an investigation would take 12 to 16 months.
NTSB used 3D laser scanner to scan entire intersection which will be used to create diagrams and models to analyze the accident.
Toxicology tests on both the bus driver and dump truck driver are still pending. Investigators are talking to children on the bus to see where they were sitting and if they had seatbelts on.
There have been no charges filed at this time as the investigation continues.
The crash happened around 8:05 a.m. Thursday, February 16th. One student was killed and another 17 students were injured when a bus carrying Chesterfield Elementary School students was hit by a dump truck at the intersection of Bordentown Chesterfield Road (Route 528) and Old York Road in Chesterfield Township.
At the news conference at Friday, Kotowski said the bus driver pulled ahead of the stop sign to see before pulling out.
"As the school bus travelled north on Old York Road, and reached the intersection with County Route 528, it stopped forward of the stop limit sign and moved forward into the intersection. The school bus driver stated to investigators he never saw the Mack truck which was approaching the intersection from the west. The Mack truck driver observed the school bus as it started to enter the intersection," said Kotowski.
"The line of site evaluation determined that, in some locations, the line of site was obstructed due to environmental features of the intersection," Kotowski said.
The dump truck, which had the right-of-way, hit the bus - spinning it around. The bus then hit a utility pole.
The student killed was 11-year-old Isabelle Tezsla. Her triplet sisters, Sophie and Natalie, were among the injured. Natalie was released from the hospital on Wednesday while Sophie was still reported to be in critical condition on Friday.
Another boy who was injured in the crash, 11-year-old Jonathan Zdybel, was also reported to still be in critical condition on Friday.
Chesterfield is still reeling from the tragedy and, in an effort to raise money to help the families affected, local florist Sharon Bentley is selling bows in Chesterfield Elementary's colors.
"As a parent and a grandparent, I just can't imagine what they're going through and I just want to show the kids we support them and their families," Bentley said.
With all that's been going on the Tezsla family has not yet held funeral services for Isabelle. Those services are expected to take place sometime next week.
On Tuesday, the Tezsla family issued a statement, saying:
"There are no words to express the gratitude and appreciation that we have for the kindness and professionalism that our rescue workers, doctors and nurses have shown our girls. ?In addition, the outpouring of love and support that we have received, in particular from everyone in our community and the surrounding communities, has touched us profoundly. We thank you for your continued prayers for our Isabelle, Sophie and Natalie."