SAN FRANCISCO (AP) — Police are trying to determine whether a fire near a Bay Area Rapid Transit station that shut down train service between San Francisco and Oakland was intentionally set.

Investigators are looking for three people seen near a construction site moments before the fire began early Thursday. The blaze damaged BART’s electrical equipment.

The fire hampered train service for more than 13 hours as thousands of people scrambled to find other ways to get across the bay.

The fire began shortly after a security guard watching the construction site was harassed by three teens or young men.

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