Ex-USC Football Star -- Thwarted Home Invasion ... Cops On Hunt for Suspects

Frightening moment for a former USC football star -- when two men tried to break into his L.A. home ... while he was INSIDE ... and it was all captured on video.

TMZ Sports spoke with Alex Holmes -- who played tight end for the Trojans during their monster 2004 season -- who says he was hanging out on March 1st when two guys began casing his home.

The entire scene was captured on surveillance ... you can see the two guys ringing the doorbell to see if anyone is inside. When nobody answered, they snuck around to the backyard.

The men put on gloves (no fingerprints) and moved a table to try to enter the house through a 2nd story window ... but set off an alarm and eventually fled the scene.

Holmes was inside the house during the entire incident -- and called police, who raced to the scene moments after the guys bolted.

"I almost feel bad for the kids," Holmes says ... "As soon as they climbed up and opened that window, the alarm went off and they ran away."

The USC alum says it's the second time his house has been targeted in less than a year.