As they exited The Standard hotel, Solange, 27, looked "mad as hell," the onlooker tells PEOPLE of seeing the trio immediately following the altercation that happened at around 2:30 a.m. on May 6. Solange was surprisingly "not disheveled" as she got into the small sedan.
"They all went up to the same car," the onlooker added. Solange, who was walking a few steps in front of the couple, entered first. But once Jay Z, 44, got to the car, he hesitated getting in and eventually "walked down the block and got in another car." Meanwhile, Beyoncé, 32, quickly stepped into the waiting car that carried her sister.
The reason for the initial confrontation between Solange and Jay Z remains unknown but the emotional toll of the fight on the younger Knowles sister was evident.
"Usually she's all smiles," the onlooker says of Solange. "But she was not feeling it. Her face told it all."