It happened around 8 a.m. Wednesday as the car driver was trying to merge onto Summit Bridge Road at Brennan Boulevard.
Crews used the Jaws of Life to delicately tear apart a vehicle to get to the driver trapped inside.
"You're trying to piece together how you pull the car apart that is not designed to be pulled apart, without hurting someone who's already seriously injured," said Asst. Chief Brandon Speakman with the Christiana Fire Company.
Officials say there were about a dozen students from Appoquinimink High School, as well as the driver and a bus attendant, on board at the time of the crash.
The students onboard were between the ages of 14 and 17 years old.
Garrett McManus was there as it all went down. He was on his way to work when the crash happened, so he stopped to help the students to safety.
"I think they were in a bit of a shock and they seemed to be stargazed," McManus said. "We were able to pry the doors open and they were able to get off."
No students were injured, according to Appoquinimink School District officials.
Injuries reported after crash involving school bus in New Castle Co.
However, the 75-year-old bus driver -- who has been with the district for five years-- was transported by Christiana Care Life Net Helicopter to Christiana Hospital in Stanton for neck, back and possible internal injuries. He is said to be in serious condition.
The 18-year-old woman was also taken to Christiana Hospital on board a Delaware State Police Helicopter. First responders spent nearly two hours working to extract her from the crushed vehicle. She is said to be in critical condition.
"[The car] was in pretty bad shape and I wasn't sure what I was going to find, but as I crawled through the back window, I was able to speak with her," McManus recalled. "She was, you know, younger, a little scared, obviously. I was just trying to keep her calm until the paramedics were able to get there."
"I know she's in critical condition, but hopefully we provided her the opportunity to walk away at some point," Speakman said.
The students were released to their families.
The incident is currently under investigation by the Delaware State Police.