VALLEJO (CBS) – A 4-alarm vegetation fire erupted in a rural area of Mare Island near Vallejo early Wednesday morning burned 10 acres, authorities said.

Firefighters were dispatched for a smoke investigation just after 3 a.m. before a working fire was reported at 3:40 a.m. The response quickly was elevated to 4 alarms as the blaze gained ground in the Red Flag Warning fire conditions.

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At least 20 firefighters were at the scene on the south end of the island at the Mare Island preserve – with others, including Cal Fire crews, dispatched as mutual aid.

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Fire officials said the blaze may have been started by someone who cut down two PG&E power poles.

Access to the rural area was difficult. Single-track roads, ridges and cliffs were slowing the firefighters’ response.

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No evacuations have been ordered.