At least 78 bodies were stacked up at one time inside the Masonic hall at Railroad Avenue and Market Street in Newhall, aka Hap-A-Lan dance dall, which was converted into one of several makeshift morgues along the St. Francis floodpath. Volunteers were already setting up improvised slabs inside the building at 4 a.m. on March 13, 1928, before the flood had even reached the Pacific Ocean.

Los Angeles Times photograph (negative), from the Los Angeles Times Photographic Archive, Department of Special Collections, Charles E. Young Research Library, UCLA. Notes on negative sleeve read:

The St. Francis Dam was a 200-foot high concrete gravity-arch dam built between 1924 and 1926 in [San] Francisquito Canyon (near present-day Castaic and Santa Clarita). The dam collapsed on March 12, 1928 at two and a half minutes before midnight. The resulting flood killed more than 600 residents plus an unknown number of itinerant farm workers camped in San Francisquito Canyon, making it the 2nd greatest loss of life in California after the 1906 San Francisco earthquake. It is considered the worst American civil engineering failure in the 20th century.

Temporary morgues for flood victims were established and Piru, Santa Paula, Filmore, Oxnard, Newhall, Ventura and Bakersfield. Up to March 18, 273 bodies had been recovered.

The location of the morgue is provided in a hand drawn map published in the Los Angeles Times, 14 Mar. 1928: 2. The 1880's building was located at the northwest corner of Railroad Ave. and Market St. in Newhall. It had been the J.O. Newhall general store, the Gulley-Swall general store, the El Dorado saloon and, at the time of the flood, the Hap-A-Lan dance club. After its use as a morgue it was torn down and in 1931 the county courthouse was built on the property.

Bodies of twelve flood victims enshrouded in sheets and resting on inclined wooden boards in an improvised morgue in Newhall.

Further reading.

Seven miles up San Francisquito Canyon Road from today's Copper Hill Drive, construction on the 700-foot-long, 205-foot-high St. Francis Dam started in August 1924. With a 12.5 billion-gallon capacity, the reservoir began to fill with water on March 1, 1926. It was completed two months later.

At 11:57:30 p.m. on March 12, 1928, the dam failed, sending a 180-foot-high wall of water crashing down San Francisquito Canyon. An estimated 431 people lay dead by the time the floodwaters reached the Pacific Ocean south of Ventura 5½ hours later.

It was the second-worst disaster in California history, after the great San Francisco earthquake and fire of 1906, in terms of lives lost — and America's worst civil engineering failure of the 20th Century.