The outage was reported shortly before 4:20 a.m. and affected customers between Pearl and Willow streets from the Alameda Towne Centre to the Alameda/Oakland Estuary, with some portions of Bay Farm Island affected as well, according to utility officials.
The outage was apparently caused by some sort of equipment failure, but the cause remains under investigation, said Sherri Hong, assistant general manager of customer resources for Alameda Municipal Power.
Power lines fell on a street, causing a fire that was "so hot that it burned the asphalt," Hong said.
No one was injured by the fallen power line, she said.
Utility crews responded and restored power to about 3,800 customers by 5:51 a.m. The remaining 3,000 customers had their power restored as of 6:29 a.m., Hong said.
Crews remained at the scene as of 8 a.m. to repair the power line and investigate the cause of the outage, she said.