Cal defensive lineman Ted Agu died Friday morning after a teamwide supervised workout. He was 21 years old.

According to team physician Casey Batten, who spoke alongside Athletic Director Sandy Barbour and head coach Sonny Dykes at a short media briefing at Haas Pavilion on Friday afternoon, Agu and the rest of the Cal football team were running near Bowles Hall, about 150 yards from California Memorial Stadium. The training staff noticed Agu was having difficulty completing the workout. He immediately stopped working out at the behest of the training staff. At the time, Agu was responsive and hydrating.

The training staff placed him on a cart and transported him back to Memorial Stadium. As they reached the north tunnel, Agu became unresponsive. Emergency medical services were called, and “high-quality” CPR was administered on him until emergency medical staff members arrived on the scene. Once they arrived, an automated external defibrillator was attached to Agu. He was then transported to Alta Bates Summit Medical Center.

At that point, Batten was alerted of the situation and, according to him, is still gathering details. Batten could not divulge any further medical details for legal reasons but did say that “(Agu) has never had any (medical) problems with any workout or practice.”

“I think this is certainly one of those tragedies that no one can understand and comprehend,” Dykes said. “He just had a passion and energy for life that was contagious. It will be deeply missed. Our players loved him dearly, and he was a big part of our family. Now, our family members are going to have to rely on each other to get through this period as best we can.”

The junior, a public health major from Bakersfield, Calif., joined the football team in 2010 and redshirted his freshman year. After appearing in five total games in 2011 and 2012, Agu played in seven games this past season, in which he contributed six tackles.

“We lost an incredible young man,” Barbour said. “Our student-athletes have lost a brother who they stood shoulder to shoulder with in the classroom, on the athletic field and in the community.”

Current and former Cal players took to social media to express their condolences:

Quarterback Jared Goff said on Twitter: “One of the nicest, most hard working, and joyful people to be around. You will be greatly missed. RIP Ted”

Wide receiver Kenny Lawler also tweeted: “Lost a brother today. Im so hurt to know that I will never get to go to battle with you bruh. You were a great person! Rest in paradise Ted”

Former wide receiver and current San Diego Chargers player Keenan Allen posted on Instagram: “Cherish these moments we have in life, you never know when your journey will end. We lost a great person this morning but gained a another angel. RIP Ted Agu #CALFamily”

Senior staff writer Michael Rosen contributed to this report.