Tommy Huxley played Sunday at the festival with his band, Tommy Huxley's Blues Avenue, and when the first shots were fired, they were breaking down their equipment. Huxley tells us Gilroy cops were on the scene seconds later and searching for the shooter.

He gives a recap of how the terrifying incident unfolded, saying at first ... he thought he was hearing fireworks, but soon realized what was happening as people scrambled.

It sounds like a complete 180 from the good vibes being shared right before all this -- you can see Tommy and his band jamming out and people having a great time.

The moment people started running from nearby stages was also captured when the shooting first started, and it gives you a sense of just how scary it was. Another band was in the middle of performing when shots were heard, and people ran for their lives.

As you know, 3 people were killed and 12 others injured.

Listen to how Huxley describes Gilroy PD's response though -- sounds like 4 officers were frantically trying to get to the gunman and end the threat, which they ultimately did. The suspected  19-year-old shooter was shot dead in a standoff with police.

Authorities say the shooter used an AK-47-style rifle, which he purchased legally in Nevada earlier this month. Witnesses have said he was wearing fatigues, and that he was shooting at random. Two children -- aged 6 and 13 -- were among the fatalities.