From TMZ:

NFL legend Junior Seau was found dead in his home in Oceanside, CA ... and a law enforcement source at the scene tells us cops believe he shot himself.

Seau was 43-years-old ... and leaves behind 3 kids and an ex-wife.

Cops are currently at Seau's home -- located in San Diego County -- and were seen talking with a man who was inside the house and appeared distraught.

Sources tell us ... Seau died of a self-inflicted gunshot wound to the chest.