Two people were killed and two others were injured when multiple gunshots were fired at a shopping center in Fort Myers, Florida, on Tuesday night, authorities said.

"It does not appear to be a random act of violence," Lee County Sheriff Carmine Marceno said late Tuesday. He gave no further information.

None of the victims was identified, and the condition of the wounded wasn't immediately available.

NBC affiliate WBBH quoted a woman at the scene who said she was celebrating her birthday inside the restaurant Society at Bell Tower Shops when someone shot her husband in the chest as she was paying her bill. She told the station that the shooter then shot and killed her son as he tried to run away.

Nestor Montoya, a reporter for the station, posted a photo on Twitter showing numerous emergency vehicles gathered in the complex's parking lot, saying multiple shots were heard.

A witness told the News-Press newspaper that he heard at least 10 shots and that he and other patrons were locked inside a restaurant at the scene.