I was standing outside in our backyard trying to get a glimpse of a fourth of July fireworks show to the South, however, I could not see anything. I turned to the North to go back inside, where there is usually nothing but a mountain range, I saw two bright green lights ascending straight up from the mountain. The lights were so bright and large, I thought a helicopter would be flying over my head in a second. Instead the vehicle stopped it's straight up vertical assent in midair and hovered there completely silent and changed colors from green to red once stationary. There it stayed completely still and silent for several minutes. I yelled for my husband to come outside and he did. As he walked out of our patio door, he said, "What is that?" But he was looking in the wrong direction. I was facing west looking at the mountain range and he was facing east looking at the same mountain range. He was now telling me to look at what he was seeing and was I telling him to turn around and look at what I was seeing. He finally did so and then the vehicle which was stationary and red, turned green again and descended back down into the mountain range. He next looked back to the East to see if what he had originally seen was still there and it was not. He said, "Call me if it comes back, I am going to get my camera." It wasn't but a few minutes when I yelled back into the house that it was back, as it was bright green again and raising straight up out of the mountain range. He was now outside with his Nikon and a tripod which he positioned on our patio dining table. Once ascended, the vehicle turned red again and was perfectly still for 20 minutes plus. My son and his girlfriend had time to come outside, pull up patio chairs, get binoculars, go back inside to get their jackets as we watched the vehicle hover in midair for 25 minutes. I then spotted a small airplane rounding and banking straight towards us and the unknown craft. At this exact point, the craft moved slightly, then made a 360 turn, turned from red to green and descended back down into the mountain range and finally out of slight. I thought as soon as the plane passed, it would reemerge again, but then realized that everyone who had been turned East to watch various firework shows in the valley, were now most likely moving around and driving around and if the craft had enjoyed 30 minutes of privacy, that was now over, as well as, the fireworks. Needless to say, it did not reemerge. Many things went through my mind as to what this could be. A very large drone videotaping the San Gabriel Valley and Inland Empire firework shows, or a friendly UFO, who picked the perfect time to play a visit. Either way, we captured 5 videos and enjoyed watching whatever it was, more than we would have enjoyed watching fireworks and sitting in traffic.