(CNN)Jim Fassel, who coached the NFL's New York Giants from 1997 to 2003, passed away Monday at age 71, the Giants announced in a press release.
A spokesperson for the Giants said the team had been informed by close friends of Fassel's family.
Fassel, who had been living outside of Las Vegas, was taken to a hospital with chest pains Monday, where he died of a heart attack while under sedation, according to the Giants, who cited numerous media reports.
Fassel led the Giants to the playoffs three times during his tenure with the team including a Super Bowl appearance in 2001, where New York lost to the Baltimore Ravens in Super Bowl XXXV.
He coached at the collegiate and professional level for 30 years, with stints as the head coach at the University of Utah and assistant coaching roles with the Denver Broncos, Oakland Raiders, Arizona Cardinals, and Baltimore Ravens.
Current Ravens coach John Harbaugh paid his respects to Fassel in a statement Tuesday and said that although he never coached with Fassel, he "always respected and appreciated his approach to coaching and the way he treated his players."
Fassel coached Hall of Famer John Elway as an offensive coordinator at Stanford and with the Denver Broncos.
The Broncos said in a statement, "We're saddened to hear of the passing of former Broncos Offensive Coordinator (1993-1994) Jim Fassel. Our hearts go out to the Fassel family."
But it was Fassel's seven seasons with the Giants which he most treasured.
"It was a great time, a great time," Fassel said in an interview with the Giants in 2014.
"People ask me, 'Wasn't the media awful to you?' No, I'm friends with a lot of them. I respect the media. They have a job to do. I'll tell you what, I was with (five) different franchises (including Baltimore, where he served as an assistant post-Giants), but the Giants is how I learned to coach in the NFL, mainly from (the late general manager and Pro Football Hall of Famer) George Young. They run it right. They put the marbles in a row to win."
Fassel was the head coach of the New York team at the time of the 9/11 terrorist attacks in 2001. He was at the forefront of the Giants' efforts to help the city recover.
"(Former Mayor Rudy) Giuliani's office asked me if I would come over and just walk around and shake the hands and tell them that we're supporting all these guys," Fassel said.
"I went over there three or four days afterward and it was unbelievable. You're standing there and this space is just wide open. I asked them, 'What am I going to do?' They said, 'You can cheer them up. People recognize you, you can just support them.' So I did. And it did work. That's how I first got involved with some firemen. Even the ones from out-of-state, mainly some from California recognized me, and I stopped and talked to them. Those guys looked like they hadn't slept in days, they were dirty. I was just saying, 'Thanks guys for what you're doing here.' You try to do a little something for them."