The fire was reported on Monday at 2:34 a.m. at the Marina Supermarket at 2181 Doolittle Drive.
It took nearly two hours to fully control the fire. Flames erupted from the supermarket and spread to another business, Thrifty Medical Supply, in the same strip mall.
At one point the roof of the grocery store collapsed and the resulting pressure blew the front windows out of the store.
At least 16 residents were evacuated from an apartment building that's 10-feet away from the supermarket that burned down. The residents have provided information to fire investigators that may help them figure out what started the fire.
The Marina Supermarket was quickly demolished Tuesday, leaving a very large pile of debris. Firefighters have been working to put out spot fires and keep dust down with water.
First responders and neighbors told investigators they smelled gasoline or a gasoline-type odor about the time the store erupted in flames. That has raised suspicion this may be a case of arson, especially because the damage to the market and to an adjacent store exceeds $1 million.
The Bureau of Alcohol, Tobacco and Firearms will be lending its analytical help to the Alameda County Fire Department and San Leandro police. "The benefit of having a partnership with the local bureau of ATF is all of those tools that can identify different levels of gases or accelerants that may have been used either in a container or in an outdoor area," Alameda County Information Officer Aisha Knowles said.
A video recording is also being reviewed from two surveillance cameras at Joe Jaber's Empire Smoke Shop. There is no person of interest identified so far. "Hopefully they can find out if somebody set it or not," Jaber said.
Jaber's Empire Smoke Shop, a coffee shop and nail salon have all been yellow-tagged, which means access is limited.
Once again, security cameras are showing their value as an investigative tool. "You shouldn't have to worry about cameras if you're doing nothing wrong," Jabra said.
Alameda County fire investigators are working with San Leandro police and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to determine the cause of the blaze.
Bay City News contributed to this story.