A man who is suspected of gunning down an ex-girlfriend outside the Resorts World Casino in Queens early Tuesday was fatally shot by police after an hours-long manhunt, authorities said. 

Dalton Branch, 51, shot 55-year-old girlfriend Patricia Mohammed multiple times in the torso when he found her in the car with another man at about 2:20 a.m., said a law enforcement official with knowledge of the incident. She was pronounced dead at a hospital. The suspect then fled in a white Dodge Charger, police said.

After a search located Branch in East New York, police confronted the suspect who opened fire on officers; the police returned fire, killing the hulking ex-con. 

NYPD Chief of Detectives Robert Boyce told reporters that the bloody chain of events began about 2:20 a.m. in the casino parking lot when Branch pulled up in a white Dodge Charger and fired one shot at Mohammed as she was talking with a man. The man started to run away as Mohammed got into her car, apparently to flee or shield herself.

Branch then got out of his car, went up to Mohammed, an immigrant from Trinidad, and fired a .380-caliber Beretta handgun three times, striking her each time, Boyce said.

After Branch fired again at Mohammed, with whom he once had a relationship, he got back into his car. Branch then began driving around the parking lot looking for the fleeing man, who Boyce said wasn't a current boyfriend of the dead woman. Branch missed his intended target, who was his former supervisor at the Trans Express Bus Co., who then immediately called police, according to Boyce. Mohammed had also worked for a time at the bus company, Boyce said.

"At different points during the night he [Branch] texts this individual, his old boss, taunting him, calling himself the 'grim reaper,' " Boyce said.

Shortly before 5 a.m., cops tracked Branch to the area in the 800 block of Pennsylvania Avenue in East New York, about two blocks from where he grew up and 3 miles from the casino.

"He made statements he was going out hard" in a call to a relative of Mohammed, Boyce said.

According to a preliminary investigation of the Brooklyn shooting scene, Branch began firing from inside his vehicle, then stepped out to continue shooting, Boyce said.

Police officers returned fired, unloading about 20 bullets and hitting Branch multiple times. The suspect was taking to Brookdale Hospital where he was pronounced dead. 

Police said a .380 caliber semi-automatic firearm and ammunition were recovered at the parking lot.

-- With Newsday