Kwamie Lassiter, a former Arizona Cardinals safety, died Sunday with the cause of death still to be officially revealed. He was 49 years old at the time of his death.

Lassiter was an undrafted safety, who forged a 10-year NFL career, which included eight years with the Cardinals, whom he helped make the playoffs for the first time since moving to Arizona in 1998 when he made four interceptions in their final regular season game victory over the San Diego Chargers.

"We were all devastated to learn of Kwamie’s passing today and our hearts go out to all of his family and friends," Cardinals team president Michael Bidwill said in a statement. "Kwamie came to the Cardinals as an undrafted rookie free agent. He not only became a key contributor to our team for eight seasons but continued to make an impact on this community after his playing days ended. He will be missed greatly."

The safety arrived in Arizona as a 26-year-old rookie, who worked his way into the first-team before playing eight seasons in Arizona. He left the team as a free agent in 2002 before playing 10 games for the Chargers in 2003 and four games for the St. Louis Rams in 2004 before calling time on his career.

Kwamie Lassiter
Kwamie Lassiter (L) died on Sunday at age 49. In this picture, Lassiter #42 and Hanik Milligan #31 of the San Diego Chargers have a drink of Gatorade during a break at Chargers' training camp July 29, 2003 at the Home Depot Center in Carson, California. Stephen Dunn/Getty Images

Lassiter recorded 588 total tackles, 24 interceptions and five fumble recoveries during his eight seasons with the Cardinals, according to ABC15 Arizona. He is survived by his wife and eight children.

The former Cardinals safety also setup the Kwamie Lassiter Foundation to raise awareness for challenges children face growing up like obesity, cancer and sickle cell. He remained active with the Cardinals even after his playing career taking part in alumni functions and working as part of the team’s radio coverage.

Despite the nature of the death not officially confirmed – former Raiders, Pittsburg Steelers defensive lineman Nolan Harrison has revealed that Lassiter suffered a heart attack while on the treadmill on Sunday.

“Very very sad day. I’m hearing from multiple guys that another former player brother died today. Kwamie Lassiter died on the treadmill today of a heart attack! He’s my age! Prayers to Erica and his family!” Harrison communicated via his official Twitter account.