(CBS SF) — Firefighters knocked out a three-alarm structure fire in San Jose Wednesday morning.

The blaze broke out at an abandoned warehouse near the intersection of Bassett and Terraine streets, according to firefighters. Flames reached at least four stories high, causing the rood to collapse.

Several homeless people sleeping in their vehicles told KPIX 5 they saw two people leaving the building at the time of the fire around 3:40 a.m.

Firefighters said there were no reported injuries. A nearby transformer exploded knocking out power to the area.

The cause of the fire is still under investigation.

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