A rapper who was once signed to 50 Cent's record label was killed after he and three others were shot in Queens Friday afternoon, law enforcement sources said.

Jamal Green, also known as Mazaradi Fox, was found unresponsive in a driveway in Springfield Gardens about 4 p.m., the sources say. The 42-year-old had gunshot wounds to the chest and was pronounced dead at the scene.

According to MTV.com, Green signed with 50 Cent's G-Unit record label in 2007 and appeared in mixtapes with the "In Da Club" rapper. He never released an official album and was released from the label in 2008. 

50 Cent tweeted his condolences Friday.

"Saddened by the news of Mazaradi's tragic passing," the rapper said. "My thoughts and prayers go out to his family and friends."

The survivors were taken to Jamaica Medical Center.