"All indications are that the action was deliberate," said Mayor Don Freitas, "and I am disgusted by the cowardly nature of the person who perpetrated this. And the city of Antioch will be extremely aggressive in its pursuit of and prosecution of the person or persons responsible."
The one-alarm fire, which occurred early Sunday morning in the mosque building on East 18th Street, caused more than $200,000 in damage.
"The investigation is ongoing, and there is a lead that is being followed," said Emily Hopkins, spokeswoman for the Contra Costa County Fire Protection District.
The mosque has been the target of other violence in recent years, including graffiti as well as a break-in last week. Two years ago city officials met with mosque representatives to show support after the mosque received threatening phone calls.
Abdul Rahman, chairman of the board of the Islamic Center of the East Bay, stopped short of calling the fire a hate-crime.
"We have in the past shrugged off the other incidents as pranks by kids, but maybe we should have taken it more seriously," said Rahman.
"It's hard to discount that it's more than that. The community is outraged by this and scared too, especially the children."
Councilman Arne Simonsen offered the city's help in relocating the congregation to temporary quarters. Pastors of two local churches and the owners of a Pittsburg restaurant and the El Campanil Theatre have stepped up to offer their facilities. The city has also presented the Nick Rodriguez Community Center as a meeting place.
"We're all very disappointed by what has occurred," said Simonsen. "But I'm pleased that the community is reaching out. These are very good folks and local business people, and we want to do all we can to get them back into operation."
Rahman said he would be meeting with city officials to decide their next move.
"We believe our immediate plan is to rebuild," said Rahman. "I'm meeting with the insurance company this week to see what's involved. But the question also becomes, do we even stay in this neighborhood?
"Membership has been down, people have started going to other mosques because of the neighborhood and safety issues. So we may decide to take a look at going somewhere else. But it's too early to tell right now.
"Overall, everyone is holding up very well. What has come out of this is an opportunity to come together as a community and a people. This is not just a religious attack; it is an attack on human beings. We're going to come out of this very strong."
The Contra Costa County Fire District has set up an arson tip line: (866) 502-7766.