Just before 11 a.m. Monday, a surveillance camera caught images of the suspect going up and down the aisles. After a couple minutes, he and the store manager cross paths, there's a brief exchange, and a sudden punch.
The suspect ran out immediately without taking anything.
Police believe the public can help identify the suspect.
"We're pretty confident whoever sees it will recognize the suspect, whether it's a family member or a friend and hopefully bring that information forward," San Leandro Police Lt. Randy Brandt said.
A co-worker says the 51-year-old manager lives in Orinda, and has been at the store for three years.
"He's a good guy, he makes everybody laugh, he tells us stories, he got this place to be a lot more lively," co-worker Xochtil Pinedo said.
Pinedo says she visited the victim in the hospital Tuesday, but was not allowed to talk to him. His family was there.
"It looks like he's going to be OK but I hope they catch the guy," Pinedo said.
San Leandro police have sent the suspects image to other law enforcement agencies as well.