A man was shot in the back behind a convenience store in Petaluma late Thursday afternoon, police said.

The 20-year-old victim was hospitalized with a single bullet wound, said Petaluma Police Sgt. Ed Crosby.

"We don't expect that he won't survive," Crosby said.

The shooting took place at about 5 p.m. behind the 7-Eleven in the Orchard Supply Hardware shopping plaza at Old Redwood Highway and North McDowell Boulevard.

There were witnesses, Crosby said late Thursday, but no one had yet been arrested.

"We're pursuing some pretty fresh leads," he said.

The man was a Sonoma County resident but it was not known whether he was from Petaluma, Crosby said.

Anyone with information that could help the investigation was asked to call 788-4372 and ask for Detective Joel Stemmer.