SAN JOSE (CBS SF) — One person was killed and four firefighters were injured fighting a three-alarm fire at an adult novelty shop in downtown San Jose Sunday night, a fire investigators believe may have been intentionally set.

The fire caused serious damage to the Adult Superstore, an adult novelties shop at 25 E. Santa Clara Street, and the AK’s In & Out Mini Market next door.

READ MORE: Downsized But Not Out, Dreamforce Conference Set to Boost Business in San Francisco

Authorities said a man was standing outside shop, wielding a sledgehammer and threatening to burn down the building.

“He came back and entered the business and set fire to the building in multiple places,” San Jose fire Capt. Mitch Matlow said.
Matlow said the man – possibly a disgruntled employee of one of those businesses, or an upset customer, or someone else – may have set the fire and died in the basement during the fire.

READ MORE: Emmy Awards: 'The Crown' Dominates with Seven Wins

The owners of a mini-mart next door to the shop called the fire department at about 5:30 p.m. Sunday and a firefighting crew was already on scene checking on the threats when the blaze erupted.

Matlow said he did not know the extent of the firefighters’ injuries.

The fire was declared under control at 9:56 p.m. Sunday, Matlow said, and mop-up operations continued as of 10:45 p.m. Sunday.

In addition to those two businesses being damaged, some vacant spaces above those businesses sustained some damages as well.

MORE NEWS: Flames Reach Ancient Sequoias; Crews in Pitched Battle to Save Giant Forest Grove

The investigation into who died and how the fire started and spread was in its earliest stages late Sunday night.