Three men who tossed what investigators describe as "incendiary devices" through the front window of a Willow Street apartment Tuesday night fled from the neighborhood in a waiting vehicle, a witness told police.
No one was inside the apartment when the arson occurred about 10:25 p.m.
Investigators do not know why the suspects targeted the unit, which is in the 1100 block of the street, Alameda police Lt. Bill Scott said.
The fire caused about $30,000 worth of damage to the duplex structure and about $3,000 to the apartment's contents, Fire Division Mike Fisher said Thursday.
A neighbor called 911 after noticing fire coming from inside the ground-floor unit and the suspects running off.
They fled in what may have been a Toyota MR2 that was last seen heading eastbound on San Antonio Avenue, Scott said.
The witness described all three suspects as males wearing dark hooded sweat shirts. They are believed to have thrown three devices through the window.
A woman, 33, and her sons, who are ages 6 and 2, were living in the apartment, Scott said. They moved into the unit within the last three months and did not have any problems with neighbors, he added.
In the wake of the arson, however, the family moved out and now is staying with relatives in Alameda, Fisher said.
Among those investigating the case is the Bureau of Alcohol, Tobacco, Firearms and Explosives.
Deputy Fire Chief Chris Reilly said firefighters dispatched three engines, two trucks, an ambulance and a duty chief to the scene on Tuesday night.
Investigators declined to comment on what accelerant was used or how the devices were made.
Anyone with information is asked to call Alameda police at 510-337-8340.
Reach Peter Hegarty at firstname.lastname@example.org or 510-748-1654.