Trabuco Canyon, California - At least four people were killed and six wounded in a mass shooting Wednesday night at a landmark biker bar in Trabuco Canyon in Orange County, southern California, law enforcement sources said.

Authorities descended on Cook's Corner on Santiago Canyon Road after the shooting was reported around 7:30 PM PDT Wednesday.

Two sources, who spoke to The Los Angeles Times on the condition of anonymity, said the gunman was a retired Ventura County cop. As many as five people could be dead in the shooting.

Per the sources, the gunman was targeting his estranged wife. It is unclear whether the shooter followed her to the location before opening fire on the crowd, they said.

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News of the shooting brought concern from local officials and residents.

"I'm heartbroken by the news of yet another mass shooting tonight, this time at Cook's Corner, a historic bar in the heart of Orange County," state Senator Dave Min, an Irvine Democrat, said in a statement.

"My heart breaks for the families and loved ones of the victims."

Cook's Corner has been a popular spot with bikers since the 1970s.