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.

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.

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.

No evacuations have been ordered.