The bee swarm was reported around 4 p.m.
No injuries were reported and authorities have since responded to the pier. ABC7's Chris Christi was near the pier at the time and said the swarm startled his family.
"My wife and I were sitting on the beach with our friends. My friends were actually falling asleep, taking a little nap, we were watching the kids. All of a sudden, thousands and thousands of these critters, it didn't even occur to me that they were bees at first," he said. "They almost seemed like light moths. I mean thousands of them. I wasn't rattled, but my wife was going crazy. I jumped on her and covered her up, and then the swarm kept on going. We were just next to the Manhattan Beach Pier and they just flew away. I honestly didn't think anything of it, and then we heard later on that it was actually a swarm of aggressive bees."
It's unclear when the pier will reopen.
This is a developing story. This article will continue to be updated as more information becomes available.