A man was seriously injured when he was stabbed outside a Brentwood bar early Friday, police said.

The injury occurred outside the El Patron bar on Suffolk Avenue just after 12:30 a.m., Suffolk County police said. Police said arriving Third Precinct officers found the victim, identified as Robert Sosa, 35, had been stabbed once in the chest.

Police did not list a hometown for Sosa.

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They said he was taken by East Brentwood Fire Department ambulance to Southside Hospital in Bay Shore where he was in serious condition. It was not clear if Sosa knew his assailant — or what events preceded the stabbing.

Police said the investigation is continuing and detectives are asking anyone with information about the stabbing to call the Third Squad at 631-854-8352 or Crime Stoppers at 800-220-8477. All calls will remain confidential, police said.