Quite an amazing story of the conflagration that engulfed the tunnel, collapsed the streets, swallowed an apartment house, and broke the water mains. From the July 25 IJ:

Two employees of Northwestern Pacific Railroad entered the 1,858-foot Puerto Suello Tunnel north of San Rafael. Their visit was routine but it was an annual inspection. So it was by one chance out of 365 that Frank E. Gladwin and James Dermit Ireland blundered on two Santa Venetia boys who had just fashioned and ignited torches made of rags, paper and sticks picked up nearby. These lads, aged only 12 and 13 years, had started several fires in the tunnel structure. Gladwin and Ireland easily put out two, then conquered a couple of others—but the fifth blazed out of their control.