Line of 10 black, round objects (each approximately the size of a car) ascending quickly from the ocean to the clouds

We live approximately 1000ft above the Pacific on a hillside. We have a clear view from the coast to Catalina Island. My son called for me to come see what he described as "pepper flakes" crossing on or near the ocean. As we watched they began to ascend. First the frontmost, then the next, etc. They were not evenly spaced but were clearly on the same path mostly. They were not connected. They rose into the clouds until we could no longer see them. Took about 5 minutes. I assumed they were large drones or weather balloons, but I can't find anything that fits. I'd love to hear a reasonable explanation for what we saw. This was observed by myself, my 11 year old son, and my 15 year old daughter. The image is the area of the sighting but I didn't take a photo of the event, at the time not thinking it was unusual.