Numerous unknown objects flying in a cluster high over California.

It had just rained in the morning and now in the afternoon the sky was clear and without haze.  The time was between 1600 and 1630 about an hour before the sun sets.  
I was in my backyard working in the garden when I happened to look up and see some seagulls circling above.  Then further up in the sky a bright spot caught my eye.  Then another one and another until there was a bunch of them.  They were traveling northwest to southwest from my location.  
At first I thought they might have been airplanes but I could not make out any wings.  They were very high in the sky so I thought maybe that might be why I could not see any.  The light I saw from them appeared to be reflection of the sun from something metallic. Most were not blinking but rather shown steady as a reflection.  However, there were a few in the center of the cluster that had a red glow that increased and decreased in intensity.  
They were not in any formation.  They were scattered in an elongated bunch, some apart, some were close together.  
After a minute or so I decided to try and count them. I got to ten but started to lose the front ones flying into the southwest.  I estimate that there were maybe 18 to 25.  
They looked like stars.  Some brighter than others, but flying as a group.