Explosion collapses part of building; 4 seriously hurt

An explosion caused part of a building in Sylmar to collapse on Tuesday, causing at least four serious injuries.

The blast occurred at a one-story building at 12349 Gladstone Ave., according to the Los Angeles Fire Department.

Firefighters are on scene and believe more people might be trapped inside the building. A search is ongoing.

No other details were immediately available, an LAFD officials said.

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-- Andrew Blankstein (Twitter: @anblanx)