SAN DIEGO (AP) — Police are investigating a huge midnight water-gun fight that left the historic lily pond at Balboa Park trashed and partly drained, causing an estimated $10,000 in damage.

At least 1,500 people took part in the fight early Sunday that was organized on social media, the newspaper U-T San Diego (bit.ly/NrQAbp) reported.

Organizers specifically urged participants to avoid the landmark lily pond but authorities say some trampled new landscaping, killed koi fish, destroyed ornate floating Victorian lilies, collapsed some planters and broke a pipe that caused the water level to fall drastically.

"Like every San Diegan, I am appalled by the complete disregard for our iconic park by these delinquents," Mayor Jerry Sanders said in a statement. "The damage they did to the century-old lily pond and the mess they left behind is unacceptable. We will hold those who did this accountable for their actions — which may be criminal — and for every penny it costs to return this area to its original beauty."

The view of the lily pond in front of the wood-lath Botanical Building is one of the most photographed sites in Balboa Park, according to its online history.

The pond was built in 1915 for the Panama-California Exposition, which celebrated the opening of the Panama Canal. During World War II, when many park buildings were taken over by a naval hospital, the pond was used as a rehabilitation pool.

The organization Friends of Balboa Park sought online donations to fund repairs and U-T San Diego reported that organizers of the event were also asking people to donate money to cover the damages.

The park, which dates to 1868, contains gardens, museums, performing arts venues, recreation facilities and trails.