Videos uploaded onto social media showed black helicopters flying low between buildings in downtown LA.
Other footage showed Black Hawks and Little Birds landing on buildings before releasing armed forces.
Erica Gallo of Lincoln Heights told ABC: “We don't think it was much higher than the steeple of the church across the street.
“They were low - low enough where you could see inside. I do think it would be nice to get a heads up you know?
“Nowadays you just never know what's happening and we're talking about it.
"Everybody has a fear especially after 9/11 happened when you see helicopters or airplanes that are flying too low.”
Leslie Ruiz added: “Four smaller helicopters in the front but the lights are all turned off and there was only red lights in each one of them and then another military helicopter came in - it was much bigger.”