Tracy police Officer Alex Contreras, who did lifesaving CPR on Heather knocked on the door and hugged the eighth grader before she walked past a line of officers in the driveway clapping and cheering her on.

“I’m just shocked,” she said. “I’m grateful for what they did to help save me.”

Heather was taking a test at Art Freiler School on Sept. 22 when classmates say they heard heavy breathing, saw her slump over her desk, and then collapse on the floor.

“It was just so scary because she just fell out of her chair and no one knew what was going on,” friend McKenna Adamo said. “All of us were just praying and hoping for the best.”

Heather stopped breathing. Her lips turned blue. And the principal and Contreras started CPR until paramedics arrived.

It wasn’t until 24 hours later that Heather regained consciousness in the hospital, her parents previously told KTVU.

For more than three weeks, she’s undergone tests and surgery to have a defibrillator implanted in her. It is not clear what may have caused her sudden cardiac arrest.

One of Heather’s best friends remembers the frantic moments in class when she called 911 and spoke with a dispatcher.

“I told her we had a student that was passed out and that we needed help and I told them the address,” Malyna Torres-Melton said. “It wasn’t the same when she was gone and everybody’s happy to see her today.”

Sirens and horns blared as Heather’s motorcade showed up at the school Monday to find fire trucks, firefighters, paramedics, school leaders, friends and family anxiously waiting for her arrival.

One by one, first responders shook hands or hugged Heather and offered kind words including “I’m proud of you,” and “You’re awesome.”

Heather quickly became overwhelmed as her father, Derek Freligh began to tear up and shouted for everyone to gather around, so he could share his feelings.

“I can’t tell you how thankful we are as a family that everybody did their job that day,” he said. “[Your] training kicked in, everybody kept their composure, and we had a miracle turnout. That doesn’t always happen and that means the world to us…thank you so much.”

Freligh is an Alameda County Sheriff’s deputy and said he understands when seconds count, as do the dozens of emergency personnel who rallied around Heather.

“These are the high-stress moments that we train for,” paramedic Mason Vickers said. “This is a really good outcome…so to be able to see it and celebrate it is an awesome thing.”

Care was seen and shown by her closest classmates who had T-shirts made in her honor, sporting her number 7 she wears on the basketball court.

“It feels really great because I get to have my friend back,” said friend Joey Russell. “It sort of feels normal again.”

An active and athletic teenager, Heather is wearing a sling for at least several weeks to avoid removing the wires connecting her defibrillator to her heart.

“I’m just so happy that you’re back,” Adamo said of Heather. “I love you so much and I’m so grateful.”

Heather cried. She laughed. And she said she was just glad to be back at school.

“I never knew this many people cared,” said Heather. “Always be grateful for what you have. Cherish every moment.”

Brooks Jarosz is a reporter for KTVU. Email him at  brooks.jarosz@fox.com and follow him on Facebook and X @BrooksKTVU