A portable toilet was set on fire Thursday evening near Lake Merced, according to San Francisco police.
The fire was reported around 6 p.m. Thursday at Lake Merced and Sunset boulevards, according to police.
The San Francisco Fire Department put out the blaze, and fire officials believe it was the work of an arsonist, police said. No injuries were reported.
Two portable toilets were also set on fire in the Richmond District at Geary Boulevard and 32nd Avenue in the early morning hours on Sept. 7.
Police said there is no indication the two incidents are related.
Portable toilet fires are not an uncommon occurrence in the city.
In the fall and winter of 2008-09, 27 portable toilets were burned throughout the city; the next year, several more went up in flames.
No injuries were reported in any of those fires, but the fire department warned at the time that the blazes had the potential to spread to nearby trees and homes. The lavatories also cost about $2,500 apiece.